You can't compare the Saffer batsmen's averages to the Saffer bowling averages. You have to look at how easy the opposition bowlers find it when bowling at the home batsmen.
I did a very quick statsguru query, looking at the number of bowlers that average under 30 in a few countries. As I said, it was very quick so I looked at the last 10 years for touring bowlers that had played a minimum of 3 tests and bowled in 5 innings. (This is just because it was easy to select from the drop down menu)
WI: 21/37 -
56.76% 
SA: 12/33 bowlers averaged under 30 -
36.36%*
UAE: 9/26 -
34.62%
SL: 10/31 -
32.26%
Ban: 4/13 -
30.77%
England: 14/48 -
29.17%
NZ: 5/24 -
20.83%
India - 8/44 -
18.18%
Aus: 7/40 -
17.5%
*(One of these is Michael Clarke who averages 10.33 for taking 3 wickets in 19.5 overs so doesn't really count as a bowler. Without him it's 34.38%)
Zim: 3/4 - 75% (Not enough tests played in Zimbabwe to get a decent sample size)
Yes, the claim that South Africa is a tough place to bat holds up to this rough and ready analysis but it appears that the UAE is just as difficult so the records of Pakistani batsmen ought to be re-evaluated
The Windies being far and away the easiest for bowlers obviously correlates to the relative strength of their test side so I had a look at the likelihood of home bowlers averaging under 30.
SA: 12/20 -
60%
Aus: 11/21 -
52.38%
Eng: 9/23 -
39.13%
Ind: 6/19 -
31.58%
UAE: 5/16 -
31.25%
Zim: 4/14 -
28.57%
WI: 6/23 -
26.09%
NZ: 6/24 -
25%
SL: 3/19 -
15.79%
Ban: 3/23 -
13.04%
Then because what the hell, I just subtracted the away percentage from the home numbers to get an idea of home track bullying.
Aus:
34.88
SA:
25.38
Ind:
13.4
Eng:
9.96
NZ:
4.17
UAE:
-3.37
SL:
-16.47
Ban:
-17.73
WI:
-30.67
Zim:
-46.43
So basically, Australia have been huge home track bullies, India too but not nearly as much.
<B>Saffers bowlers LOVE bowling at home more than anybody but touring bowlers also have success there that they don't find in Australia and India.</B>
The away averages being higher than the home ones for SL/Ban/WI reflects the frailty of their test sides over the last 10 years.
UAE is the most balanced host nation of the lot when it comes to 'home' vs away bowlers and I was surprised to see that away bowlers are more likely to average under 30 considering how we went so long without losing a series.