Disabling GT via the launcher only removes GT ores and tools. It leaves any "harder" (stupidly resource intensive) recipes that DON'T depend on GT things in place, because the config file is separate from the mod itself.
This claim is so absolutely factually incorrect, and so easy to test, that you should be ashamed of yourself for posting it. Of course such factual incorrectness is rampant in the blind level of GregTech hate present in some.
Disabling the mod in the FTB launcher mod list will mean that mod doesn't get loaded at all. Thus the config file doesn't even get read, present or not, much less acted upon. There is no code in memory to do any of it.