To be fair, earlier the boys did say they didn't know if it was a "curse or love", so that's probably why the dude is freaking out, since there's no wayin his mind anyways that Tanaka-san is indirectly confessing to him.
@DeoAduivante It did get serialized, but the Pixiv version is still on-going for whatever reason. In fact, raws for chapter 31 were just published yesterday.