Wow. You are in a very unpleasant position.
My best advice is to NOT let him move in with you. You've worked hard for your retirement, and it's not your fault that he hasn't saved up enough for his retirement years. He's simply wanting you to support him. Your daughter's opinion of him is valid.
I understand that he gives you emotional support and takes care of you sometimes, but I don't think that's enough if he hasn't been smart enough to handle his own finances. I think it would be a disaster if you let him move in.
Maybe you need to start thinking about whether or not he's good for you at this point. Surely you could find someone who is financially stable.