I agree. It simply says that the wolf cannot be declared as a target of an attack if there's another legal hero target available. If the monster is ranged, every hero in LOS of said monster is a legal target. If it's melee, then any hero adjacent is a legal target. If the monster is melee and the attack you're making has reach, then any hero within 2 spaces, in LOS, is a legal target.
Note that attacks that have no target, like Sweep, would smack into the Wolf just fine regardless.
What you really should be asking is: What happens when a Blood Ape Leap Attack's through spaces containing the Wolf?
Leap Attack: This monster may move its Speed, ignoring enemy figures as it does so. When if finishes its movement, perform a single attack that targets each figure this monster moved through. Each figure rolls defense dice separately. Limit once per turn.
I'm gonna say that because no official "declaration of target" is made upon declaring this particular attack, it ignores the Stalker context. I'm open to alternate theories.