It's a timing/capability concern not a rule violation.If the Q&A you mean is this one:
A15.43 Must/may a Berserk unit enter an enemy-occupied entrenchment, if it has sufficient MF and the stacking limit is not exceeded, or may/- must it stop when it enters the enemy unit's hex, if that will allow it to engage in CC should both units be present during the CCPh?
A. It's the berserk unit's option. [Letter8]
... then I don't see how that addresses the issue of the 'two Berserk squad-stack and the 1S Foxhole'; the Q&A is about one unit and stipulates that "the stacking limit is not exceeded". In the issue at hand it's about two units zerking as a stack and a FH that has room for only one of them. I'm not saying that it's clear that the "they must move together as one combined stack" means that neither of them can enter the FH: it's just that the rules are not clear at all about this (whatever we would want them to say).
Impulses for HW's are "simultaneous" yet you may move a single unit into an enemy location and allow the other ADJ units run on by. It's a choice..The rules allow units that move together to make different choices, this is a common concept even outside these states of specialty movement.
A mandate has been obtained and their location doesn't change.