Think approaching this objectively is the best course. Look at him as you would any other random person.
The whole “brother” and “family” shouldn’t be a consideration anywhere in the near term because you have zero interactions or history with him.
First, they need to be an acquaintance.
Second, they need to be a friend
Third, maybe there’s potential for a family consideration that could be in the works.
Sounds like so far, they aren’t a good acquaintance which isn’t going to make a good friend. The rest is out of the question.
Best pass this round. Maybe some years down the road, things will be different and he’ll have a different approach.