If you want to kill off a main character, episode 9 out of 14 isn't the place to do it. And furthermore, they're probably not done with Tilly's story yet. If you don't like Tilly, I can see you not wanting to see more. I'm interested in seeing her grow and be someone that Burnham and Stamets can talk to.
I like the characters. Some of you don't. That's the difference. So, if they hypothetically did kill her off, I'd prefer they did it in an episode that had more weight to it than something like this one, which is somewhere in the middle.
We'll agree to disagree. Largely because I think this argument is nothing more than an argument for its own sake. Tilly is the most optimistic character in the show. That you're rooting for her to be killed off is, frankly, surprising.
Anyone complaining about killing off Ariam instead of Tilly is complaining about what they would have rather have had the story be about than what it actually was.