Ugh, the statement "I see you as a man" is loaded with assumptions that it's enough to make your head explode before you even figure out where to start, lol.
Of course, there's the issue of some transmen wanting to retain the distinction between themselves and cismen (transmale as its own sex). There's other transmales who simply use the identifier "man" with cis people just to circumvent the confusion of telling them the body they inhabit doesn't necessarily make them a man...or a woman. There's other trans folks who don't identify within the binary even if they've undergone HRT and/or SRS. So she'd be getting a very different response depending on the trans person/transguy I think.
But if the comment is towards a transguy who identifies strictly as a man, then I think the simplest response is what you said, "well, that's because he is a man." Though the whole statement is enough to make a person want to give them a Trans 101 crash course.
@Empress, I get why some might think that the statement is meant to reassure some trans people that they "pass," or reassure us that at least someone sees us as the sex and/or gender that we actually are. Honestly, though, I think something like "ignore them" instead of "I see you as a man" is more supportive. Then again I may be the wrong person to respond to this. I feel there are a lot of problems with the politics of "passing" and the need to reassure trans people that they "pass" when it comes to dealing with trans people as a generalized group (vs. a trans person as an individual with individual thoughts/circumstances), so I don't see that sort of support necessary for myself, anyway. It depends on how that trans person interacts with their own sex/gender.
Edit: Also wanted to express my initial "omg, it's Calpernia Addams!" reaction. I had no clue she had a youtube channel. I'm totally subscribing to her now. I hearts me some Calpernia
