Because you had a gunner at the time, then no, that would not be allowed. Since you had a gunner, you wouldn't be allowed to get out and defend yourself anymore - you'd have to rely on your gunner to do that.
Now, if you had been solo, yes you could get out to defend yourself since they stuck you with a plasma nade.
We understand it takes time to learn all the 'peculiarities' of racing rules, but as long as you mean well and are willing to listen, you should find things will work out. Don't sweat it, just learn from it and move on