Yes, they can shoot.
I've used them like this before, in a very shooty battlewagon (to maximise the use for a non-moving BW).
Downside is that if the BW takes a hit they can't shoot (shaken, stunned..)
Add in a
KFF mek, and the chances of this drop markedly, and let you repair your BW too.
That said it's not that effective, as that BW will have a huge glowing 'KILL ME' sign above it