This is pure speculation, but it seems that GitHub's ownership by Microsoft causes them to be significantly more strict with the types of content that they are comfortable hosting. Expect this to continue as they expand up and down the stack; once their npm acquisition closes you'll see this there too. I think this should be a wake-up call to anyone staking their open source project on GitHub — if I let someone from…
That's why i push my git to both github and gitlab simultaneously. Git makes this easy to do, there is no reason to not use both.