I can find no information about what limit they’re claiming. You can use a maximum of 5 different Apple ID simultaneously on a device but that’s pretty obscure.
it is 5 devices that you can use personally with an Apple ID (so, you as a single person can own 5 devices that can receive things you've paid for on the app store, like music and programs.).
Distribution restrictions on top of GPL and they don't own the copyright on all the code without a CLA which prevents licensing under something other than GPL for the App Store.
Sorry, but I'm not familiar with this – could you share more please?