That argument would have a lot more weight if people were arguing she should be sent to Hell, but... no one is, as far as I can tell. Karlach isn't suicidal. She doesn't choose to die, she'd rather die than go back to Avernus. There's a huge difference.
How is it not "respecting her choice" to want an option for her to not die, when she's literally always talking about how much she loves being alive?