Bad idea.
The grenade can do 310 damage.
If you could time your toss precisely enough to throw it into alien's face, it would instantly kill everything smaller than a Tyrant, which it would leave with 90 health.
It would then take 18 rifle bullets to kill the Tyrant at that point.
It might work out if the grenade was super nerfed, though, although I think most players like it the way it is.