It really would be horrible if he ended up in the wrong home. I have a little girl who is about the same size as him, and she plays well with most small dogs, and really bosses around my boy who is just under 5lbs. It is amazing how these little ones make up for it in attitude. I just really watch her, if the play gets to rough then she usually comes running for me
Having one this small is like having a puppy you just continue to take all the same precautions you would with say a 12-16week pup cause they don't "grow" out of it. I think it would be worth it to give him a try and see how he does with Maxwell.