I would have thought it a bit odd to ask that kind of question on this forum- I mean, if the attraction is muscular women then I'm sure most guys here would be more like fascinated/interested than intimidated.
Ah, well, you see, that sort of depends on the guy.
I will confess that I'm a geek. Love being one

But, when I was at school I was fairly bad around girls. There are probably more reasons then me being a geek, e.g., it was an all boys school until 6th Form/College when my school went co-ed.
Not to say I'm making a sweeping statement, I like to think I'm better now, and can prove it with a Facebook or IM contact list, but then theres still the subject of the muscular chick.
I have before considered that I might be mildly intimidated, my track record with actually dating or whatever is not great, so it's probably more me feeling insecure about me being mildly out of shape since I got to Uni and then pining over someone who has put the effort in and will look down on me for not etc etc.
Having said that, I have been going out with my girlfriend for 2 years, and she's a dancer with a nice (i.e., toned) physique, but she's not bigger then me so maybe I'm not talking bull?
Either way, I still think that I might feel intimidated by an FBB. A woman named Marina Cornwall is a Personal trainer at my gym, she won a Natural FBB competition a few years back I think, and I'm a bit intimidated to go up and speak to her. I'd feel ashamed at the state of my 'abs' compared to hers...