I do tend to think that guys with only female friends are like a delicate flower. :]
However, if he is straight as a ruler! Then I wouldn't compare him with a girl having only male friends, whereas I take in account that "MOST" guys befriend only those girls whom they are attracted to, and if possible would have something more than a friendship with them. and that's not just me saying it. I actually posted a question here a few months back (on my deleted profile) where most here agreed that they only befriended girls whom they were interested in as more than just friends. As oppose to girls who do actually befriend guys for their friendship and not because they are expecting something more in a not too distant future. & There is also a video of this somewhere on the internet where they randomly ask guys and girls about this stuff, and most of the guys answered that they would actually want something more, whereas the girls had no idea.
Anyway! Either he's gay, therefore he has a bunch of female friends. OR he's straight and is interested in most of his lady friends as something more, but they remain friends because none of them are willing to have something more with him. I'd say you're wasting your time if you actually want some type of romantic relationship with him. But sometimes things do turn out! So good luck with that!