I don't know the full details, but I don't believe games using Honey Select can be released on steam.
It's not even a question of whether Steam accepts it or not but whether the developer(s) accept it or will actually want to put it on Steam... that's why it's a suggestion as it would be cool (there are several h scene games on Steam, just see it)
Yes, there are several H games on steam. But if you notice none of them use the Honey Select engine.
it could be the first... like I said suggestion to the developer(s)