You can't control what your son likes. Even if you take the dolls away, he will find a way to play with other items that are similar. I think you are doing a good job by allowing him to play with what he wants--he will be who he is supposed to be, and you can't change that... I used to work in daycare, and there were several boys there that were more interested in dolls than typical "boy toys". On the flip side, I have a 4 year old daughter who couldn't care less about dolls or the Disney Princesses, even though all her friends LOVE that stuff...her favorite color is blue, and she likes to play with animals (horses) and do puzzles. I just let her be who she is.
Have you ever read the children's book "William's Doll"? It sounds just like your situation. The little boy wants to play with dolls, and his whole family is against it, until the grandmother finally gets him a doll and points out that he can love it and care for it so he will someday be a great dad. Try to think of it in those terms, and tell your husband not to worry!