Making use of Saru's death sense in dealing with threats is just as plausible as using Troi's empathic abilities on the bridge.
Kor
I think it would be a lot easier to buy if they'd said he could detect hostility and aggression -- things happening in real time, like Troi did -- rather than saying he can foretell the future about something so specific. Talking about death like it's riding in on a pale horse seems dumb.
If they're going to suggest Saru has supernatural powers, I'd rather they give a supernatural explanation instead of trying to dress it up In pseudo-scientific terms.