Of course, a hot spot also causes updrafts, so your thought there is still valid.
Personally, I think combining solar PV with solar thermal is an interesting option. When your panels are often seeing temperatures in excess of 90C (that part I am confident is true), it seems like using a heat exchange fluid to both cool the panels (improving efficiency and lifetime) and deliver that heat to a heat engine or use as a preheater for a steam generation system is interesting.
I think possibly more interesting for residential, where a 90C heat source preheating your residential water before your water heater could significantly increase the effective efficiency of your panels. You generate high value electricity from as much light power as you can, and use the waste heat to decrease your use of electricity/gas for heating. Win-win, and the cost is just some heat exchangers and tubing.
Sounds like this mega plant is designed with a fair amount of redundant capacity; for cloudy days, maintenance etc. If so, this may facilitate "real world scale" testing of approaches like yours without unduly affecting "production."
However, using that warmed water as a preheat for another process is perfectly valid.