Hmm. As a bi person I wouldn't say this is intrinsically true, but in many ways yes. Because not being a woman means you're operating from all the male conditioning you've been subjected to from childhood. You can't guess how a woman "thinks" so to speak, so there's more work involved.
Being sexually fluid is somehow different than being bisexual? I can't tell the difference.
Sexual fluidity is definitely more a concept than a "label", so it's a little odd that he consistently uses it that way. I'd wager that he just doesn't want to label himself as bisexual for whatever reason.