You say all of that, but there is no actual point for them to explore considering that he's not actually in a stressful situation like those women who had been there for a year. By all accounts, his experience is much more tame in comparison to what the girls had to go through since they had been abducted and put into a lifeless city with a bunch of strangers they didn't know. On top of that, their bodies were altered without their permission and in some ways that some of them didn't even like (See: Maddie). On top of that, their libidos were considerably enhanced and they were forced to deal with that for over a year, which the MC doesn't even have to deal with since there's a literal sex aquarium of women set before him. So, what is there for him to struggle with in this scenario? There's nothing to be stressed out about.
Does he have to contend with the fact that he's in a strange place? Yes. However, the Overseers and the women have made a point of making him feel as welcome as possible. What about needing to worry about being seen as a walking dildo by some of the women? Yeah, that's something he has to contend with. However, most of the women he's already met have made a point of making clear that even if he is a hunk, they won't stand for being treated like crap. I mean, for fuck's sake, so many of the women and even the one in the most recent update made a point of how the "over-confident hunk type" isn't all that attractive. Hell, most of the women have insisted upon receiving nothing but respect from him, even if he is the man come to please the hungry masses. To make matters even worse, the literal head of the harem convent made a point of expressing that while they have a problem, she respected the way he didn't treat the girls like literal fuck dolls and just wanted to be his own person. However, she also made a point of impressing upon him how important it was to ensure that the women in the convent he's in don't go insane from having no release from their sexual desires. Compared to them, his life is absolutely fine.
So, that being said, it doesn't make sense that the MC wants to act like a fucking priest when the women throw themselves at him. It's so stupid, considering that there's no basis for this line of thought since he has no issue with ogling their bodies or even fantasizing about doing all kinds of pervy stuff to them. Which, in the end, only goes to show that the MC isn't really worried about his own sanity. His excuses are not only dumb, but they're irrelevant, since this situation is obviously much better than the life he left. I mean, the women that he left behind gave him the feeling that they were all crazy and unreliable, but most of the women he's met have been nothing but respectful and understanding of being in the situation he's in. Not only that, but he also doesn't have to worry about eating or sleeping as much, since the Overseers have enhanced his body to the limit to become the perfect sex partner. All of his physical needs are met and some of the women are equipped to deal with his mental ones, which they've even offered their support to help him with! So, everything he's said about his situation has been absolute bullshit!
The criticisms that people have about the dude being a coward or just straight up gay are totally accurate and its the entire fault of the devs for making him that way. I get that they want to show that this is a situation where one's sanity would be tested, but the guy isn't actually going through anything particularly stressful. He is in the most shape he's been in his entire life and not only that, there are a group of women who have basically treated him like a literal king. They respect him and most of them have done their best to help him cope with the situation. He is in a fantasy paradise for a man like himself who came from a life where the women he was around only gave him bad impressions of them. Now there is a chance for him to actually get a better understanding of the women around him and the ones he left behind, all while getting his dick wet and basically being cared for completely until he completes his task. It's not a bad life at all. Yet, the dude acts like he can't stomach the idea of getting pussy unless the women basically force him into having sex with them. It's so stupid! Just make a story about the guy slowly, but very surely, getting used to his new life and adjusting to the fact that he's being lavished with more female attention that he's ever gotten in his life. And that his life would be arguably a lot worse if he HADN'T been kidnapped, as he would've died a "loser" as you so eloquently put it.