I mean if you are required to release a server dev kit, or at least make best efforts to release one, you can release what code you have and go “Here are the interfaces, but I can’t legally release this code because I don’t own it, so someone else is going to have to create an alternative”.

It’s about making it easier for other devs to make up for the gaps, rather than going “Nope! Proprietary code, can’t do anything!”