Cosmetic for You but not for your customers, IMHO.
Cosmetic is cosmetic, meaning it won't affect any actual operation.
FYI: the simulator does not quit. After start simulator i can do a flight, but wihout GSX. SIM is working properly, there is no CTD or any other issues.
Your error log showed it did. Maybe it was just a completely different issue but, from GSX point of view, it happened during a quit. Have you possibly restart it or quit the couatl engine yourself ?
OK, lets go through complete process:
1. FSX is starting, with loading default flight (called in fsx.cfg as "situation"). When loading is finished, gsx is usable, which means all operations are possible, and gsx icon in windows systray appears.
2. To get the FSX main menu and arrange flight that you wish, you need to escape default loaded flight. And probably this situation is called int the log as "quit simulator". But the simulator is still running, on the main menu level.
3. Once the new flight is set and launched, GSX is no longer available: no icos, no menu, etc.
As you can see, the issue is not just cosmetic, and results in the inability to use the GSX normally in every flight, as it was before the update.
I hope it was helpful in understanding the problem...