What is Aurelia? Why would it be sanctioned?
It looks like a JS frontend framework. I've never used it. I have no idea why it would be sanctioned. Bizarrely Aurelia 1.0 at https://github.com/aurelia/framework has a banner across its top indicating trade sanctions, but the new version Aurelia 2.0 doesn't https://github.com/aurelia/aurelia . Aurelia's developers suspect it's because they have contributors from sanctioned countries. That's the first I've ever hear…
Given the number of huge FOSS projects on Github, it's feasible to imagine that many major repos have code contributed by people from sanctioned countries.
I have no idea what their motive is, but it smells really political to me. I could see Github's argument if they violated labor laws by hiring or contracting with individuals illegally, but that doesn't sound like what happened here.