I know Eli didn't do this out of concern for Leslie's saftey, since it's been obvious since the beginning that she has none of that. But I'd like to think that, on top of her fear of losing her place, maybe there was also a bit of self-preservation involved in her decision here. If Leslie snapped and used her powers after they'd just tried to kill her again, it's very likely that she would just kill them all.
Maybe I'm an optimist, but I find the idea of Eli helping Leslie for the sake of self-preservation to be at least a small step forward. Still totally self-focused, but at least that would be less... petty.