First - the insurance advice you received doesn't sound right. Unless I read it wrong, your vehicle was parked and your employee operated vehicle caused 100% of the damage. So...why would you have a deductible twice? Your insurance covers the accident via Collision on the vehicle causing the accident and via Liability to fix the vehicle he damaged. There's almost always a deductible on a collision loss, but never ever ever ever on a liability loss. Think about it as though your guy whacked an unrelated vehicle - that "other guy" would never accept a settlement involving a deductible!
That said - if he doesn't seem like an accident prone klutz, and you feel as strongly as you seem to about him being an excellent employee... then keep him on! Give his good work a chance to make you money! Otherwise if you cut and run, he can never make you any money.
Good luck!
This^^^
I was thinking the same thing about the insurance, seemed like the ins CO is trying to put the claim all on you, and then hike your rate...
Also thinking the same thing about letting the guy make you some money...but I would still run as a team and watch him like a hawk for at least a month worth of runs...let him sweat it, if he can't handle it then you don't want him working for you