There's definitely no clearance for the neck area to rotate as is.
Unless the front of the torso also folds down/opens up, leaving this mechanism clear to turn. Then you can turn it 90 degrees, fold up the next head's neck panel (they seem to all be on pinned joints) and close the chest up again. Or you open the back, this whole dial telescopes out that way, turn, fold up neck/new head, push the assembly back in and close up the back. That big rivet in the center seems like it has to do something. (Also, there seems to be a slight rail on the opening, presumably on both sides, that could slide alongside and lock in the flipped-up neck/head base.)
It's pretty involved for something not really associated with the brand and characters. But then, the whole notion of having heads based on the gang instead of having full-on Titan Masters based on them (and for THAT there seems to be no room here, even in storage) has that odd disconnect too.
In altmode I guess they really are making out in the back of that van. But eh, they're more than old enough.