I do not have any in depth knowledge of this particular parasite however I think it is unlikely that this parasite has any effect on the behavior of its host like Toxoplasma gondii(which encysts inside neural cells). The larvae of P. tenuis "occasionally" hatches in the brain however the larvae migrate out which makes behavioral change unlikely. Additionally, it would not be to the worms advantage for the deer to die because the life cycle requires the larvae to be passed through the feces. Ideally the deer would live as long as possible(or as long as the adult worm is alive and can lay eggs)

The cause of the "madness" in moose is likely due to similar situations seen with other parasitic worms. Off-target but similar hosts of these worms often experience adverse symptoms not found in the intended host. The larvae of these worms can get "lost" because of a lack of the appropriate biological markers that allow them to navigate the host properly.

Edit: I would hypothesize that those worm larvae that occasionally hatch in the brains of moose are unable to migrate out due to the above scenario and just stay in the brain moving around and causing damage and/or inflammation which results in the madness symptoms.

For example- If pork tapeworm(Taenia Solium) eggs (the stage excreted in human feces) are ingested by the intended pig host, the larvae harmlessly encyst in muscle until the meat is ingested by a human. If a human ingests the egg stage(from human feces), the larvae get "lost" and can end up encysting in brain tissue which causes neurocysticercosis (seizures and other neorological symptoms or death).