I thoroughly disagree. If Stannis wasn’t willing to burn strangers to help his army deal with the snows at the Crofter’s Village, I don’t think an ordinary obstacle is going to motivate him to do the thing he would most abhor. Second, as I’ve stated, Shireen doesn’t come south from the Wall unless there’s somewhere sage for his heir to be, like Winterfell. So I don’t think it can happen before he retakes Winterfell.
The “weird combination” I was referring to we see at work in the purely random decisions by the various Houses of the North leading up to the Battle of the Bastards: why do the Glovers refuse to aid the Starks against the Boltons, when they’re marching in Stannis’ armies in the books? Why do the Manderlys stay neutral until the conflict’s over, given their intense motivation to revenge themselves against the Freys? Why does Smalljon Umber fight for the Boltons, when the Umbers are ancient enemies of the Boltons and Umber himself died in the Red Wedding in the books?
And I don’t think Stannis is simply going to “hand over” Winterfell – there’s going to be a lot of political conflict over what Stark is going to inherit, not the instant switch of loyalties we see in Season 6.