They do apply to corporations. Allowing commercial use is part of the definition of both "open source" and "free software" so a non-commercial license is incompatible with the GPL

Without Stallman releasing an official Non-Commercial GPL (NCGPL) and allowing GPL'd software to be upgraded to it like it can be upgraded to AGPL, there's no way to merge non-commercial licensed code into GPL code without relicensing even if the non-commercial code is otherwise using a standard FOSS license.