Next healer class released should be

[GucciSan]

Because unless they overhaul the other healers they aren't going to give one healer a ranged auto attack and the others not. Which means you're advocating for one of three options:

1. Massive overhaul so all healers get a ranged auto-attack (theoretically plausible, even if it's kind of odd).
2. A blatant balance issue (this from the creators who didn't want to balance Eos and Selene, to say nothing of other things).
3. A gun that can't even be used as a proper gun (certainly possible, but being that overtly misleading seems like such a poor choice, though if anything this seems the most likely at this juncture).

None of those are good options. I suppose the first is fine, but there isn't any reason to expect it will happen at this juncture.

They could just make it a bolt-action rifle, or a single-shot grenade launcher. You'd still have "cast-times" but it's just an animation of your character reloading. And if it's one of those two now you have a way of justifying different ammo types, i.e. flame rounds vs healing salve shells for a grenade launcher.