I would have handled it better, not with lawyers but with PR people.

my point is that it’s probably a PR person sending a precrafted email or letter like this and you shouldnt take it seriously for a nonprofit hobby project unless it contains a summons. they’re asking nicely before they escalate, but most companies contract out very expensive lawyers to handle these things that bill by the minute and they aren’t going to waste it on a hobby site with even mild pushback or no response. otherwise they’d just sue.