Gotta agree with the OP and I said the same back in 2014 when Amir's return began to look possible.
The simple fact of the matter is, I don't even think its Amir's return itself that caused it, but the manner of it.
Mohammed Amir didn't have to start from the bottom and work 10X harder than anyone else around him to regain his trust and spot as he should have done. He was labelled one the greatest talents in the game continuously in his absence, some people maintained he was set up or just a naive innocent teenager when convicted, whatever theory or excuse was used one thing was common in them all = Amir wasn't fully responsible. Then he returned to domestic cricket and after some time his spot which, lets be realistic, was virtually guaranteed to him, was returned to him, and he was restored to exactly where he was in 2010, the spearhead of Pakistan's attack in all 3 formats. His return was seen by almost all as inevitable and many fans here were incredibly excited, letting their love of his talent overcome his actions. Videos were oozed over of his domestic return, he's still got it, can't wait to see him back in the green shirt where he belongs etc etc
5 years passed, the majority of the domestic and international players in 2010 were still around and it was as if nothing had changed. The kid who had it all in 2010 and dragged his country's name through the mud was back again with the responsibility of representing one of cricket's biggest names. You can argue he suffered jail, you can argue he was punished enough, point is 5 years after his offence, not particularly long when you consider he's still only 25 and has a decade at least left in him, he was back as if nothing had happened, profiting off a responsibility he tarnished in the past. And his two colleagues were both regularly on TV again and pushing for recalls themselves, hell Asif was doing punditry when he in particular should've been confined to the dustbin of history.
It's obviously foolish to say this recent event is Amir's fault, It's not, I highly doubt he'd be stupid enough to get involved again. But the example it set was awful. Commit the greatest crime an international cricketer can really commit, defrauding his own nation and fans and seeking self profit as a result of that, and have a significant amount of your fanbase praise you,defend you or call for your instant return for the team and to the highest stage, and you can after 5 years be back again if you're good enough and move on. Sorry but it's not a deterrence. The BCCI to their credit has always at least recently been incredibly tough on fixing. Look at Sreesanth, he was last week barred from playing Scottish club cricket by the BCCI, compare that to the PCB at every ICC meeting from 2013-2015 raising the case of Amir and requesting special treatment and clear guidelines and such on his behalf. Its clear that in India = fixing you're absolutely done, cricket is a no go anymore, you had your chance, goodbye, you've served your time and deserve to go back into society, but cricket as a career path is closed to you for good as you violated the trust placed in you as a cricketer, just like a bank frauder won't be allowed manage money again after violating the trust in his profession. PCB = if you're good enough we'll welcome you back, TV stations looking for controversy and views will hire you to give your opinions and the audience will tune in, you'll be live on TV again playing and succeeding in domestics. I'm sorry but that attitude means that if someone is offered enough of an incentive they'll take the risk, knowing if they're good enough they may yet get a second, third etc chance.
There are obviously other factors to be fair, and the PCB to their credit has actually done well in isolating this and nailing it so early on in the PSL, but the damage has already been done. Australians will be waking up to headlines all but stating that the best batsman Pakistan had in the tour is being flown home on suspicion of fixing, and that's 7 years of hard tireless work done to rebuild a shattered image flushed down the drain in a single headline.
When these offences continue to happen there can only be a couple of reasons. One is that the players aren't educated, which simply doesn't stack up anymore since the PCB gave all players a list of bookies and procedures to follow, and there have been several high profile cases with regards to McCullum,Peterson and so in in recent times. Another potential cause is money, but since those under suspicion are well paid by Pakistani standards and stood to gain a lovely pay check in the PSL anyway that doesn't stack either. Quite simply its a case of greed on the player's behalf mixed with the impression that the PCB's stance against fixing isn't strong enough, as evidenced by the fact that Butt is next in line to get a call up to LO sides based on domestic form and Asif also has his fans calling for his return, and Amir is obviously right back where he left off in 2010.
Nobody is saying the 3 in 2010 deserve to be harrassed forever, but there is a very realistic demand that if someone violated the trust placed in him as part of his profession e.g a charity manager embezzling funds and caught doing so, that he will be barred from that profession and ever being in such a position of authority again.
Fixing cannot and never will be entirely rooted out, some people are just greedy, but it can be significantly reduced by strong measures and punishments against it. PCB and the Pakistan cricket fraternity now need to look long and hard and ask themselves if the 2010 trio were dealt harshly enough in cricket terms, and maybe considering just banning all offenders for life if it wants to build up a no nonsense approach. The fact they've caught them so early leads me to believe that unlike before there actually is a desire to root out this behaviour in Pakistan cricket, but the punishments need to reflect this.