I guess there are three separate questions here:
(a) Is it dangerous to watch bareback porn?
Answer: No! At least no more dangerous than the dangers of porn consumption in general.
(b) Is a sexual partner who watches bareback porn likely to be more risky in their real-life behaviour than one who only watches condom porn, other things being equal?
Answer: I would have to say possibly yes. People who are fastidious about only watching condom porn are probably going to be more fastidious in their sex lives, other things being equal. I say this as someone who overwhelmingly prefers bareback porn and (when on prep and with chosen partners) likes bareback in real life. The problem with judging sex partners by their porn preferences, just from a practical perspective, is that it might not be a big enough factor in a person's real life behaviour to be worth worrying about compared to other things.
(c) Is it ethical to watch bareback porn if you consider it too risky to do yourself?
Answer: On a simple level, no maybe it isn't. Porn actors (unlike professional sportspeople or adventurers) generally do what they do for money and not for the love of it. If we consider an action unacceptably risky we generally shouldn't ask others to do it on our behalf for money.
However, this assumes that our personal judgment of risk must be a Kantian universal judgment for all humans. It might be, but it seems reasonable for someone to say: "I personally wouldn't accept the 1 in a Million chance of catching HIV whilst on prep having sex with other, frequently tested, partners also on prep, but it's still a low enough risk that it's not irrational for a porn actor to take it for good money, even though I personally wouldn't. Therefore, if such people want to accept that risk, I shall watch their material."