He still holds admin powers, which people might easily dismiss but I've had experience in past times with rogue former admins causing serious problems - you never leave inactive users with admin powers no matter how trustworthy they seem.
He came back just to make other people admins and then disappeared again, which also raises questions over the ownership of the instance. It's best security practice to have users with minimal necessary powers so if someone's not admining they shouldn't have admin powers since that increases the attack surface. Also the way the contingency plans were aborted the second he lifted a finger with no explanation or apology sort of rubbed me up the wrong way.
I'm having a bit of a moan, I wouldn't want anyone to make a decision like that purely on my account, you should make your own decision. Maybe feddit.uk will turn out fine, I hope it does, I'm just explaining why I don't use it. lemmy.zip seems to be a responsibly run instance with similar federation policies to feddit.uk