My son has done this exact thing before but be was a young 4 then (still is) so my answer might be different when he's five.
I told him he could come out when he cleaned it up. He got himself REALLY worked up about it being a bigger mess than he could clean himself (which I'm sure he believed, it was a huge mess). So we had a talk about how sometimes when we're mad we make really big messes. Messes so big we can't clean them ourselves, and we really need help. I want him to know he can always come to me for helo, even if he caused his big messy problem. So I "helped" him by standing in the doorway and asking "do you want to pick up this one first or this one?" for about fifteen minutes.
Now that we KNOW he can do that himself (he knows where things go and only has access to enough clothes for a week at a time), I would fully expect him to clean it up himself. And I would address it calmly and compassionately by saying "I'm really disappointed that you've missed out on so much family time tonight because you chose not to pick up your clothes. We're eating dinner in ten minutes and will have a plate for you if you get your clothes put away. Then it will be bedtime at 7 just like every night. It's up to you! But I really hope you'll choose to clean up so you can join us. :-)"
Love & Logic is my fave parenting book.