There's precedent in the Ork
FAQ for "passive" psychic abilities to be used on the embarked squad:
Warpath: Applies as normal to the embarked unit.
'Ere we go: Applies as normal to the embarked unit. no effect on the vehicle.
Waaagh!: Applies as normal.
And the two "shooting" style powers "following the normal rules for passengers firing."
Trust me, with some of the rumoured new psychic
SM abilities and
LRs being nigh invincible, I'd rather that you couldn't use psychic powers from a transport...