EDIT: I had minimal exposure to Snap, sometimes Snap was my only option to get some software on Linux in a decent version and without getting into dependency hell while trying to compile it (why can't someone make a package manager for C/C++?). I do see the issue with proprietary servers though.
Can you elaborate a little? I imagined this meant something like Visual Studio Code' Marketplace (which doesn't allow non Microsoft products to connect), but I don't see anything about that on Snap's TOS.
To be clear, I'm not saying you're wrong or anything, I'm just trying to understand.
I don't think it's a TOS thing, just a lack of open source server software? To the best of my knowledge, it's just not possible to host my own snap server. At least, I didn't find any solution when I looked. Which seems weird, for an open source operating system.