the thing is, he's not family. It just happens you share a father. Blood does not make a bond - it just doesn't, however much you want it to, and tbh I think you're building this up in your mind to the point where you have expectations of this brother sister relationship along the lines that it could be the same as your relationship with your other siblings. But it can't be the same. YOu didn't grow up together, you don't share a mother, you have nothing in common apart from the fact you have the same father, and you don't have the bond that you had with your other brothers growing up, so even if you met you still would never develop the same kind of relationship.
Aside from that, your brother has most likely learned things about his father that he didn't know, and didn't expect, that his father had other children that no-one knew about, that his father was the sort of man who could walk away from those children and have nothing to do with them for deckades. That's a pretty harsh thing to find out about a parent, even before you take into consideration the fact there are siblings you didn't know about.
My dad's natural father left them when my dad was fourteen. When my nan died last year my dad did some research to see if he could find out what happened to his dad. Not because he wanted to find him, but because he just wanted to know out of curiosity. It appears that he did remarry and that there are possibly more children, (I have it on good authority he was a bit of an arse and it's possible there could be several more children iyswim). Tbh I myself am curious. I wonder if there are aunts and uncles and cousins out there that I've never met, or perhaps I have met and don't know we're related, I'd love to know, although I'd never contact any of them if I found out. But my dad just has no interest what so ever. He's found out his dad died (hasn't lost any sleep over it as he was never a father to them anyway) and that's that - he doesn't want to pursue it. They're not family to him, they have no relationship, end of.