I understand where they're coming from honestly. Well, it's unfair to say they're highjacking because it's just their opinion - but it gets to a point in where it's brushing dangerously close to being so far from the devs vision and the lore that it can be considered a highjack. Like, there's no other word for it I suppose?
Yoshida wants elegant and handsome, Viera males. Handsome has long since been attributed to masculinity. You don't call a feminine guy handsome; you call him cute or pretty. You don't call a beautiful woman, handsome. If the developer wants them to be handsome, then they will be just that, handsome in terms of masculinity. Elegance doesn't = femininity either, so that's off the table. Elezen moves with elegance - all red mages fight with elegance. An assassin who is trained to waste no movement than what is needed moves with elegance. This is the image painted. Now let's talk about Matsuno's vision, where they are muscular like a boxer - with zero body fat. Yes, they won't be extremely buff - but I have a feeling people have different views when it comes to muscular. All you need to do is look back at all of final fantasy and look at the muscular males there; there's plenty to see. Imagine cloud strife, but the muscles are more defined. Midlander body type is a lot more likely, just taller with more muscle. Even if they have Omega M's body type; people need to remember that they're still going to be ripped by default.
Anyway, the point I'm making is that if you want a male Viera that isn't handsome and has no muscle development then yes, you're not supporting the devs at all. If you want a male Viera to look soft and have a sheltered life, then you're straying from the imagery put forward. Male Viera aren't cute, they're not kawaii and there honestly shouldn't be any reason for them to look extremely feminine. Their life is a sad tale of being ripped from their communities, trained to kill and survive - thrown to the wolves where most die in the final test and then only seeing another person again when they have to kill them - regardless of why that person is there, in cold blood - or to mate. And when that's done, and only then do they have the opportunity to not be lonely stoic striders by taking an apprentice. Nothing about this screams cute, feminine or the likes. It's a hard life. Any femininity they may have would be warped by scars, facial hair, grime and blood.
You could be described as highjacking a race if you're taking it extremely far from what is being envisioned by both the devs and the lore. I don't know; maybe I look too much into this as a writer. But man, I'd be disappointed if they ended up looking overly feminine. Even if I know that most who want this won't be considering the lore - and have their own RP headcanon where they wouldn't have gone through any of these hardships. Ones headcanon shouldn't trump that of the Devs or beyond what the lore allows - that goes both ways. Thankfully male Viera can leave the wood with lore that has been given to us. If it's to protect the wood, they can leave. This includes hunting down those who are a threat to the wood. Males actually leave the wood to do this, you just don't see them.
As a side note; we're fortunate that male Viera doesn't have to suffer what happened to female Aura. I'm pretty sure they get snubbed because of the two clans, and one of them being dainty in the description of lore and how most of them are princess wifus, priestesses and housewives. They didn't want to make another model just for female au'ra.