Is it just an archive or isn't it? If it is, what's so important about the community, then?

It's fine that you chose what you did, of course. It's just that that in your defending it, you can't seem to decide whether you want to have your cake or eat it.

If you wanted, this would have been a perfectly fine reason to give: "We went with GitHub because it's just what we use mostly, and other stuff not so much."