LC, I think Artscroll’s logic with the vehi noam is that, if they put it before weekday aleinu, it would look like they were condoning/supporting the practice of skipping all the other motzei Shabbos tefillos. They don’t seem to like legitimizing omissions regardless of how commonplace; I refer again the the infamous benching gray box…
As for the fact that they do have the vehi noam before aleinu in their Sphard siddur, maybe the minhag of most Chassidim is not to say the other stuff so they don’t mind condoning it there? I’m not sure.