The push modifier affects the entire object, though, right? It’s akin to a geometry shell offset, but without using a shell. So while it could help with the pokethrough on the breasts, it would also push the rest of the outfit away from the underlying Genesis figure. Depending on the clothing item, that may or may not be visually usable. (Though for the Santa Baby Dress, it’d probably be OK since it’s one piece and so wouldn’t show gaps between it and the Genesis figure elsewhere.)
I looked at the list of items created by the Santa Baby vendor, and saw that Bloodmage is another recent Genesis item from them. That, too, had problems with refusing to take dialed up breast morphs now that I think about it (the two main breast morphs I use are Breast Size and Breast Implant). With Bloodmage, I changed the design of the character I was after and worked around the pokethroughs by using the polygon group editor to make the strap around the breasts a separate material zone that I then hid to make it into a topless outfit (Bloodrites - Initiation). So what are they doing in their rigging that makes it not work well with the auto-follow morphs?
(Some might argue after looking at the linked image that I use excessive breast morph settings. (While large, they are still within realm of reason in the real world with plastic surgery. Even I don’t particularly care for the super-ginormous stuff you see in a lot of renders on dA.) But with Santa Baby, I tried using breast sizes much smaller than I normally use while experimenting with the smoothing and collision levels and still couldn’t get it pokethrough-free.)