Edit: at least in turn based mode, casting seems to work as a move action.
Vital strike cannot be used as a move action with aspect of the colloxus during demonic rage. If this is working as intended, the description of the ability should be very clear about what qualifies as an ability, because there is no obvious reason to suppose that a standard action like vital strike would not be considered an ability. Bare in mind, Zippy Magic does work with vital strike, even though vital strike is clearly not a magical ability of any kind, and the description for Zippy Magic explicitly refers to spells.
Between this not working on vital strike, and improved cleaving finish being massively bugged to the point where it usually just functions as cleaving finish, my vital strike build has been hugely gimped by bugs. I am doing well under half the attacks I should.