I think it's difficult for women to get how men just see children differently unless we're involved with them.
If a woman I'd had a one night stand with ten years ago tracked me down and told me she'd had my child, I'd be shocked, worried, guilty & angry. I'd be curious about the child but I would have no emotional connection with it. I don't know if I would want one, it's something I'd do a lot of soul searching about. I don't know if I'd choose to meet it (although would if the child wanted) - it might upset and confuse the child if it had a stable and happy home life.
However, I have two DC who I adore, who I would never lose contact with and would die for, kill for, and travel the world for. But I was the first one to hold them when they were born, even before their mum, the first one to change their nappies, I fed them, burped them, teach them stupid songs and help them with homework. That has no comparison to a child I've never met on the other side of the world. I could be the father of multiple unknown children, theoretically - I don't believe I am, but these things do happen.
A man choosing to have nothing to do with his own children who he was involved with, out of laziness or being an arse, can't really be compared with someone who finds out they have a child ten thousand miles away who is being happily raised by someone else. It may be painful occasionally, but it's not the heart-wrenching loss of a child who has been part of our lives on a daily basis.
See the guy and work out if he's telling the truth.