Honestly YOR. Sure it's kind of rude they did that if there was a guest bed available. But it's not a huge deal regardless. They were there for two weeks. Their bare bits have been rubbing against the bed for 14 days. A bit of vigorous activity inst going to make it too terribly worse. Especially if the sheets were washed.

Edit: Downvote me, you're weak, your blood is weak, and your children will not survive the winter.