A 30-second google isn't finding me a source, but I heard about the controversy from multiple people so it must have been around fandom anyway. Apparently the anime creators - I guess when promoting Welcome to the Ballroom? - were talking up the series as not being gay like Yuri on Ice. Apparently, it's not even a case of them being asked about Yuri on Ice (because I could understand getting annoyed if everyone else was constantly comparing your anime to another), they would bring it up on their own. Sort of in a "Yuri on Ice is good but too much about a gay love story" way.

Someone else told me that the anime was made even more, uh, heteronormative(?) than the manga because in the manga, sometimes the women lead the dance but the anime changed it to always be guys. No idea on the accuracy of that.

So anyway, if there were homophobic jabs made, I don't know, and it probably doesn't reflect the views of the original manga author even if there were.