Isn't Atlassian afraid of getting sued, though? It seems like a HUGE risk to take on a project like Popcorn Time. Then again, Atlassian makes millions of dollars annually.
The open source license is for self hosting, not OnDemand, so I'm not sure if there are really licensing implications there or not. Does an OSS license equate to an endorsement in a legal sense? I don't seem them generating a lot of ill-will from a PR stance.
I would actually think that providing hosting to Popcorn Time would be positive PR: people who contribute to Popcorn Time would spend the most time interacting with Stash and are unlikely to be morally opposed to Popcorn Time. While people who are opposed to Popcorn Time are much less likely to check what Popcorn Time's repo is being hosted on or who gave them a license... Basically, Atlassian's generosity would only be noticed by Popcorn Time supporters.
That being said, I'd still much rather see Popcorn Time hosted on an open-source platform like Gitlab.