Is my tort endangering himself in this furniture cover?

https://imgur.com/a/jyVyR0m

I have an outdoor weight bench that I cover with a furniture cover/tarp to protect from rain.

Fred has discovered that this tarp really captures warmth from the sun and now he absolutely loves it. I'm worried he'll wrap himself up in it and not be able to breathe or something, but no sooner have I pulled him out, he's right back in there.

Is this an issue? Are torts dumb enough to crawl in and suffocate in something like this? Or should I let him enjoy his new greenhouse?

Thanks!