I believe the thing with the father is that he cannot see "himself" as being attracted to another man, so he cannot relate to gays, but he is attracted to women, so romantically relating to lesbians is easier. I can understand him a bit - to me, even though some of my friends (even best friends, I'd say) are gays, relationship-wise they are always a bit tougher to speak to than lesbians.
That said, it's not necessarily wrong as long as he accepts that other people are different - it's just a bit of an instinct (for some weaker, for some stronger) that one needs to overcome and throw aside.