If they were so worried about being revealed, they would have contacted Hunk Ch to take down their stuff just like Koki did. Other than him, I don't know of one of the guys (that I mentioned) who has. Also, Yuuya and Kaito never even appeared with face mosaic.
There's a pretty discernible pattern of guys (big, beefy rugby/football types in particular) doing a few vids and then ducking out before getting to the types of scenes where gay stuff would be asked of them (namely the interview with the Jeopardy-looking board. not sure the name of the series, but it's well known. Kaito even did this and refused most of the hotter stuff like kissing or getting fucked in the ass).
Just as a general note about being revealed, I imagine these guys are almost never revealed (including and especially Koki) unless they inadvertently had something to do with it. The Hunk Ch guys I'm talking about are the big jocks who probably have no (out) gay friends. so how would anyone in their social circle find out unless they probably told the wrong (guy) friend who then blabbed? I mean think about. they use a fake name (just a first one, at that, no surname), fake age in some cases (Koki), have their faces obscured, and Hunk Ch isn't the only gay porn company in Japan. Even if it were huge, the average Japanese person who isn't gay probably doesn't even know it exists, much less who's on it. We all know about Hunk Ch because watching hot Japanese men do sex stuff is our niche. My point is, I think it's probably pretty rare when a guy has his Hunk Ch vids truly discovered by someone in his social circle, unless he's totally open (no face mosaic, no fake name) and making tons of works (Jin, Hiroto, etc.). More likely, he told the wrong friend that he got some cash just for fucking this girl on camera and that's what got the ball rolling