I think that with girls, there's more maintenance in cleaning up a messy diaper. I am having trouble remembering the newborn poo factor and how much of an ordeal it is, but part of me is thinking that toddler poo is more of a big deal in making sure to clean out crevices (especially if they have been hiding or sitting in it, and moving all around.) My daughter didn't really poop in her diaper after 9 or 10 months, but during this pregnancy she has had some poop issues and has secretly pooped (or let out just a little) in her undies and cleaning it up after we realize it has been a PAIN. My husband has done most of it, mostly because I was so sick and couldn't deal with untoward smells.
I guess your husband might be freaked at the thought of spreading and checking to make sure everything's clean? The thought of a close inspection is skeeving him out a bit?
I agree that he'll get used to it. She'll be his child and things should work out.
My husband never expressed that kind of reluctance or anxiety (we didn't know we were having a girl until the birth, actually), but I'm sure he knew nothing/had no experience going in. He just learned and stepped up to the plate. I'm assuming this will be the case with your husband, too.
(My thought about having a boy and dealing with genitals is, "What if it's really short and it doesn't WANT to point down?" (I've always heard to "point it down" during diaper changes.) Also, I wonder about elimination communication with a boy, trying to hold him AND point the penis down, if that's even necessary. And how that works, logistically.
But I haven't really felt freaked about actually dealing with the (hypothetical) penis, itself.
Then my son was born, and I had more important things to worry about than his genitals 
:
at mums wiping bass ackwards.
