@count @dansup Two TOSes I believe do a good job here are YouTube and Facebook. Neither guarantee "immediate deletion of all user content" on account termination/content deletion—but no one would ask them to, that's a straw man. Both services find reasonable wordings that protect both the user and the company.
See, YouTube license: https://www.youtube.com/t/terms#27dc3bf5d9 Short, simple, reasonable.
Facebook license: https://www.facebook.com/legal/terms/preview/?section_id=section_3 Pleasantly detailed, but possibly too rigid for a small site like Loops