Here’s my thoughts on why Meta Knight is so hesitant when it comes to being a good dad.
Meta Knight doesn’t want to be Kirby’s dad, he wants to protect Kirby and keep him safe, but he doesn’t want Kirby to imprint on him. This is because Kirby is the only one powerful enough to stop anyone if they turn against him and the rest of Dreamland.
Meta Knight has been possessed/controlled many times and there’s no guarantee that it won’t happen again. Kirby has stopped him every time but if Kirby starts looking up to him, he might hesitate to do what must be done.
and a possessed Meta Knight certainly won’t do the same.