Well, that's just fundamentally incorrect. Yes, by in large, it is straightforward. But, there are differences of opinions, contextual rulings, exemptions based on time and place, which obviously require a bit more thoughtfulness than might be expected.
I think it was implied that 'ability to fast' is more of an umbrella phrase, which encompasses if the person considers themselves to be fit enough to go through with the fast without being affected significantly. 
I called that "cheating bit" a stretch because you're assuming that everyone is fit and firing a 100% day-in and day-out at their jobs. As we all know, that isn't true. Many people take extended lunch breaks for the Friday prayer, but they don't get their pay docked since it's known that the prayer is an obligation. Following your argument, you could argue that many service technicians, or any other job that is physically intensive, should be paid at lower wage since they can't perform "optimally" while fasting. It's not sensible in my opinion.
There are many habits that players around the world take engage in (drinking, etc.), that obviously deteriorates their bodies gradually, and eventually, renders them as not a 100%. Yes, they may not be drinking on game day or just prior, but drinking has implications far beyond the short-term. Yet, we don't see as much policing regarding those habits, which will effect both their physical and mental headspace.
I think what people are essentially struggling to grasp with is that they consider fasting during playing as voluntary, but that is not what Rizwan necessarily believes. And he is absolutely fine in doing that since he's the better judge of his capacity.
All in all, this is a non-issue in my opinion.