I agree man. I play solo and always get these people who destroy my equipment. Either with gun or their emp grenades. I don't run emp nades because I know how it feels to have my equipment destroyed. Either it be sentry guns or as simple as bouncing Betty.
I run engineer in every class along with emp grenades. I always know who the equipment belongs to, and can't resist going after the red ones LOL
The larger issue? The whole team-killed/kick system implemented in hardcore game modes in Call of Duty is flawed.
Sometimes, you just accidentally kill 3 people on your team - it happens. You shouldn't be kicked for it eveyr single time, because of the fear that some troll could join a game and kill all of you?
The hardcore ricochet method is somewhat better, but even then, is extremely annoying.
My suggestion = implement a voting system, where you can vote to kick out teammates.
Killed 3 teammates by accident? No worries. Your teammates have the option to choose whether or not to kick you from the game, rather than to make it absolutely up to the game itself. The game isn't able to distinguish between accidental team kills and a troll.
Tying this back to the OP's issue about having friendlies destroy equipment - if someone is making a habit of it, the entire team can vote that culprit out. It also saves the OP from having to kill him and lets him focus on playing the game