+1 for destroying an asset because more than likely someone will repair it... Otherwise, there'd asset-whores, or folks whose friends are enemy commanders and let the dude blow it up, drop a supply, and continue the cycle.
I guess they figure you have 4 or 5 assets to destroy, and eventually someone will repair them so you can destroy them again... or blow them, whatever you prefer.
As for TKs... it's -4. +2 for a revive would mean -2 pts overall... just to clear up your math problems.