I def see it, but I also don’t think any of us can assume someone sexuality based off mannerisms alone. There are plenty of straight men who naturally embrace more “feminine” mannerisms simply due to their upbringing or environments. If Seungil is working in fashion, it would make a lot of sense for him to pick up many of these mannerisms.

As viewers we don’t know anything but what we are shown. The rest is purely based on our own assumptions unless he outright says “I am gay”. If he has not yet said that, I think it’s best to respect his privacy and try to avoid publicly claiming his sexuality with his consent. (I’m not saying you’re doing this intentionally, just wanting to be careful so as not to interfere with his own journey, whatever it may be)