Heh heh,
The question isn't on the ability of the bodybuilder really. It's more about the concept...
For instance, if we use comics as an example.
I think that heroes who only shoot fireballs and eye blasts from a distance, should be rather scrawny and not as muscular compared to a hero that fights hand to hand or has super strength. This matches the concept of the character, which means that they are weak when up close but strong at a distance.
It wouldn't make sense for Captain America to be scrawny since he's a hand to hand fighter with super strength. Otherwise you get the "Supergirl" effect, a scrawny toothpick who can lift tanks. Does that make much sense to you?
So when Cpt Matt is talking about some characters not being an ideal fit for muscles, it just means that some characters or people just don't look right with an enormously muscular body. Sometimes you can just tell by looking at someone's face that they wouldn't carry muscles well.
For instance, I personally don't think Jennifer Aniston would look good with big muscles and I've seen the morphs done to give me an idea. It just doesn't work for me, she's very attractive but she just doesn't seem the type that should have muscles.
Lara Croft, she would look great as perhaps a figure competitor with a six pack of abs, well defined back, and arms, but she wouldn't be as good being beefy and massive, otherwise you expect her to lift boulders. Which would be fine, but it'd be a totally different character.
Muscles simply don't work for all, that's why you get some hideous "women" with muscles and you're like "Yikes..." where as other women it suits them better and they look perfect with massive size.
Thank you, you hit it square on the head.
Another example, for me, would be Chun Li from the Streetfighter games. Paula Suzuki is wonderfully muscular, amazing shoulders and unbelievable arms, but too much to be Chun Li. On the other hand, Rebekah Kresila would be just about perfect as her.