This question seems to indicate you are using GSX the wrong way. Why you want to keep enabling/disabling GSX ? That shouldn't be necessary, at all. The only reason to have a "disable" option, was just for troubleshooting purposes, but it's not something you are supposed to do constantly.
If you want to disable GSX on a specific airport or a list of airports, the proper way is using the disable_on_airports parameter, as explained on the manual.
However, yes, the fact you cannot RE-enable GSX after having disabled it without getting an error, has already been fixed in our internal version, which will updated as soon as possible, but that doesn't mean keep disabling/re-enabling is the correct way of using it.
Is there a special reason why you want to disable the whole GSX in a session ? Are you aware that is not doing anything, or taking any memory, until you call it explicitly so ? The whole program logic runs entirely external to the sim, so it won't take either memory of CPU cycles, until you call it, and its vehicles will start to appear.
