@ Toothpaste - I think that's a little harsh. We're all artists here, with strong aesthetic preferences, and writing about something one doesn't care about is a recipe for crappy writing,. No one should force themselves to use characters or genres they dislike. If I one day get brave and create a female lust-object character it will be because I have a story idea that needs her character, not as some sort of "no pain no gain" experiment.
I was giving my advice, yes it was direct, but I was reading between the lines, and maybe I owe the OP an apology for that.
Considering his reasons for creating his main character a woman (about her strength and agility - which is faulty - and that he just thinks it's hot), considering his logic in creating her a lesbian (logic which was dubious at best), considering his age, considering he is also male, I took his inability (and lack of desire) to describe men as a straight woman might see them as less to do with a writer having literary preferences, and more of an immature (and I mean that simply as someone who is young) fear of sexualising his own sex. A fear not necessarily stemming from any kind of homophobia, but more a societal pressure that exists for guys not to comment on the appearance of other guys (women of course don't have to worry about that problem). A fear of not being manly enough, or a fear of others thinking he's gay, or a fear of his friends teasing him . . .
You also talk about creating characters that suit the story, but he has made many of his decisions about his character because he doesn't want to describe men as sexy. That to me is not being true to the character in the story, but an author imposing his own fears on a character and thus making her something that she might not have ever been simply because he's not interested in putting in the extra effort.
However, all of the above is just conjecture. Maybe he truly has no interest in writing about men as seen by a woman, maybe he truly finds it dull or uninteresting. If that is the case, sure, don't write about that. I agree with you, no one should force anything, and I wasn't saying that.
But I don't think fear is a good enough reason to not write something, nor a good enough reason to give yourself the massive challenge of writing a character from whom he is very different (as others have pointed out, being a Lesbian doesn't suddenly make you a guy dressed in women's clothes). The leap from, "Since I don't want to describe guys in a sexual way, I'll make her a lesbian" is simply not good enough a reason for me. It lacks a real understanding of . . . well a great many things.
Lastly, I ended my post, I thought, on a very encouraging level. Okay yes, I will admit to some snark at the beginning, and I am sorry for that, genuinely. But I also feel like some authors don't give themselves enough credit, that they indulge the fear instead of facing it. I think he could do it if he tried, I think he probably is talented enough, he shouldn't doubt himself like that. I hate it when people say, "I wouldn't be very good". "I wouldn't be" suggests the future. If he already knew he sucked at it he would have said, "I'm not very good at it." He hasn't even tried yet and already he's dismissing his abilities. It makes me sad when I see that.
At any rate, I did not think his reasoning sound enough to make the decision he was making, and that's why I said what I said. If after he does some more research, learns a bit more about women (their physicality, what they can and can't do), learns a bit more about lesbianism, and STILL wished to follow the path he has chosen, then by all means, go ahead.
But he shouldn't make decisions based on fear. That's just my opinion, but a strategy that has held me, at least, in good stead.