it's not necessarily seen as less masculine, but it's seen as less engaging, and (especially people who are timid themselves) people interpret it as indicative of hostility. I think "less masculine" is an oversight... Talkativeness has never been a supposed masculine trait; in fact, it's more feminine traditionally. But by talking, you negate other people's assumptions of hostility. So by being talkative, you comfort the shyer types.

Shy Girls rarely feel interest in shy Guys, but it doesn't necessarily have anything to do with masculinity. I think interpreting it as such makes it unnecessarily complex, you're making yourself more insecure, thinking that your quietness is being seen as weak. It's more just being seen as dissonant. Psychopaths can often be overly quiet, etc. Don't misinterpret accidental intimidation for others viewing you as beneath them; that's a formula for a chaotic psyche.