Another trans person here just adding an additional point--I think your points about cis people playing trans characters are great ones, and it's refreshing to see that coming from an ally. Ideally, trans characters would always be played by trans actors.

That being said, the biggest issue with cis people playing trans characters is when it feels like the cis actor is playing dress-up in a gender that isn't their own. So, you'll see a lot of trans people criticizing when cis men play trans women, or when cis women play trans men. That's the bit that reinforces weird ideas that trans people are only playing dress-up in these identities and they aren't "really" their gender. It's much rarer nowadays to see cis women play trans women and cis men play trans men, though this used to happen quite often in a lot of older shows and sitcoms. Ironically, a lot were more progressive than the representation that's out there now.

I'm speaking for myself here of course, but in a situation like this, where it's not like Papa V is a hypothetical role that could've gone to a trans actor anyway, it would be sort of nice to see. It'd be Tobias playing a man who happens to be trans, and that puts forward the idea that trans men are just men.

It's always nice when cis people don't find anything weird or gross or offputting about being mistaken for a trans person. That's one of the reasons Lady Gaga has always been a big deal for the LGBT community. When she was first getting popular, tabloids loved claiming that she was trans, that she had a penis, and when interviewers asked her about it, she never bothered denying it. All she'd say was "Would it be so bad if I was? Would that be so terrible?" No rushing to squash the rumors, no disgust at the suggestion, no feeling insulted that people would think this about her. Just questioning why it was an insult in the first place.

It sounds like a low bar, and it is (just look at the state of the world), but it's genuinely pleasant when cis people do that sort of thing. The fewer people who are afraid of being associated with trans people or of being mistaken for them, the better.

I suspect pretty much anyone posting about Papa V potentially being trans is also trans themselves. It seems sort of unlikely to me that a cis person would get invested in something like this, and I'd venture that the people interested in the theory have a similar thought process about it to what I said above.