How old are you? Because you sound pretty young. I doubt your brother is worried about you TALKING to this boy, and I am pretty sure he knows that this boy wouldn't be interested in just TALKING to you.
Do you have some valid reason to believe your brother has malicious intent? is there some motive that would make him not want what is good for you?
For the record, i have two teenagers. I never approve of a boy hanging around my girl until her older brother tells me the kid is a good one. Your parents don't know this boy the way your brother does.