The bite attack that lycanthropes have says that creatures hit with the attack must make a saving throw, not that the lycanthrope can choose to have them make a saving throw. It is an effect of the bite.
This is particularly important for wererats, which are described as being particular about who they "bless" with lycanthropy, and that "Wererats that are accidentally cursed...are quickly hunted down an killed."
So, if it's possible for a wererat to accidentally curse someone, and if their bite is described the same as any other lycanthrope, that further supports the idea that they can't "turn off" the transmission of their curse.
Finally, it's pretty consistent with the folklore and pop culture around lycanthropes that the curse is rarely transmitted fully intentionally, and that it's at most collateral damage from an attack that was meant to kill a victim that somehow survived.
...probably not in your example
The curse is a collateral effect of the lycanthrope actively biting a victim, as they would in combat, which probably means more penetration than pricking yourself on a wereraven beak. That's probably up to the DM, especially if someone grabbed said unconscious wereraven beak and went at someone with the beak.