That does not change th fact that they made the werewolf invulnerable.
Now the way I would have done it is have the time limit, made the werewolf still have its strong attacks, but vulnerable to damage and killable. However it would have major damage reduction and hit points.
It still a pretty much a killing machine but those who have the stronger weapons, such as the uber machine guns and flamethrowers, can kill it in a sustained fight. Now the ammo usage will most probably make this not a cost effective option but nonetheless the option is there.