A stunned figure can do the action "Perform a move" as it does not leave its space through this action, it only gains movement points in its pool.

So yes, a stunned creature can do the "perform a move " part of beast tamer. It has to discard the stun to actually leave the space but you can do the order

Beast Tamer -> Perform the Move

Action 1 -> Discard Stun

Then move around and have your 2nd action.

Edit: and because beast tamer is performed on your activation and not a special action the movement points go into a pool and can be spent any time on your turn - after you discard stun.