Thanks, just get on with life without grenades then 
the bind works, it just prints error messages because the bind depends on at least one of the commands failing. (first it sells the grenade if you are near the armory, so you don't drop it in your base, then it tries to throw the grenade, which won't work in your base because you just sold it, but outside the base it is still in your inventory, so it gets thrown, and finally, it tries to buy a grenade, so if you didn't have one (or you did and sold it), you do now, and just in case you didn't realize, in tremulous clicking on the nade throws it instead of equiping it like in other games)