It's a purse? How does holding a purse make you not "alpha"?

Because a purse is pretty much the definition of femininity and holding a purse for your girl (which of course is a nice gesture) is a telltale sign that you're whipped (a girl can take care of her own stuff).

It's not his.

And that's what makes it OK in your mind? Can a guy wear a skirt or a women's thong in public, but it'll be OK if it isn't his? I'm genuinely asking here b/c I don't understand why you'd bring this up

Maybe he's just secure in his manhood and doesn't care if anyone else gives a rat's ass that he's holding onto his lady's purse?

There's a difference between being secure about your manhood and not giving a shit. Holding a girl's purse while you not giving a shit about what other people think is fine. But it's not a symbol of masculinity just as sucking on a guys dick as a male is a symbol of heterosexuality. An extreme example I know. Though it just goes to show that doing the opposite of something with confidence isn't a way to reaffirm to yourself, or anyone else for that matter, that you are that something.