Looks fine by me!

The long horizontal range is definitely useful for the spear. I generally think constructive skills will be more effective in the horizontal dimension; with the destructive ones, i.e. the grenade, I'm a little more fixated on the vertical dimension (like bombing from below, denting a ceiling for a Shimmier etc.).
Thus, the Grenadier with the current arc will still only work on comparatively low ceilings, but it's high enough that I think we could design level terrain specifically made for this (without that terrain shape giving away too much about where to assign which skill).
I generally don't see that much use for throwing a spear against the ceiling, HOWEVER there is one big Shimmier-related one, the counterpart to the "Grenadier hole dents the ceiling to stop the Shimmier":
If the spear lands in the ceiling diagonally, forming a little ramp, the Shimmier can land on it and start fencing or maybe even bashing from there. Especially the Fencer at this point would be useful, because it allows to precisely what we would currently need the Laser Blaster for: A way to carve a path into a ceiling for a Shimmier to continue.
In this case, the Shimmier could carve that path himself, whereas in case of the Laser Blaster, you'd need a different lemming to do it. Of course, in the former case, three different skills are needed (Shimmier, Spear Thrower, Fencer), whereas in the latter, you only need two (Shimmier + Laser Blaster).
Thus, I don't think this type of Spear Thrower usage would make the Laser Blaster superfluous. I'm just saying it would be a way to work around this if, for some reason, we would end up not getting the Laser Blaster. (Which I don't think at this point, since it seems to be the most popular skill at this point.)