Well let's face it, by season 5 Janeway already has consistently demonstrated she's willing to play god with the lives of her crew. She was willing to let Neelix live in purgatory on a biobed rather than kill the Viidian who took his lungs. She killed Tuvix against his will to save Tuvok and Neelix pretty much because she liked them more. Declared she was willing to kill them all to keep the Kazon from getting a replicator and so on and so on.
So looking at it from that perspective, her forcing Torres to take a treatment against her will is small change. That doesn't make it any less unethical. Torres has the right to determine her own treatment or lack thereof. Even if it's silly at best to cut off your nose to spite your own face in her shoes as I think it is.
I don't think the Doctor was out of line at all to use Crell's information. Was it terrible what Crell did? Absolutely. But adding one more body to the mass grave isn't going to change what he's already done. In fact I think a sick sadist would think it's utterly hilarious that yet more people would die out of some silly twist of morality rather than live knowing that his knowledge saved them.
Does that mean I think Janeway had the right to basically force Torres to do it? No. Were I captain, I'd have encouraged her to do it, but in the end if she said no, I wouldn't force it. If it was me on the table, I would say use the SS agent's knowledge to save my life. Me dying isn't going to change anything that already happened after all.