@Perim:
Er... I still can't tell just from those panels whether the author isn't just razzing us, personally XD
But if I do take them seriously, your complaint checks out—she's (at least initially) drawn a shoujo manga for publication in a seinen magazine, full stop (well, okay—there may be some real difference in effect because of who her editor is and/or her own perceptions of her immediate audience or some such, but we can safely ignore that).
Yet the rules about using publications for demographic on mangadex and other sites stand, so, then, it's exactly like you said in the first place. Sorry =.=;