We're hard wired to be intimidated by folks bigger than us. Any shrink can tell you that. This isn't a hard question.
Most guys that are well built are that way for a reason: discipline, patience, planning, work ethic, research, education, and so on. Things many folks would do well to aspire to. Most, and I've known many, go out of their way to be nice, but, just because we might rate a 8 to 10, or whatever, it does not give you the right to get into our personal space. Often times, those folks do well in whatever they decide to pursue, but, there's also the nut cases that don't have a career, or any semblance of a balanced life and are so very narcissist as to be a real drag.
I've have to pop folks in the face for not respecting my personal space a few times, but, only after warning them numerous times.
There's really no reason to be intimidated. Most folks from politicians, to movie stars, to big muscle heads, response pretty well to normal acting folks. Fastest way to turn of a well adjusted big buy? Adoration. If we're well adjusted, and most big guys are, we don't want, nor need, adoration. Uhh. Huge turn off.
And, you need to be realistic. While a big built guy might be just fine in being friendly, if you're old and fat, or young and starving, well...you need to accept that you might well not be his type. We tend to lean towards folks that we share a common experience with, whether, it's working out or the science club, or even false belief systems.