Did I give wrong advice?

O.k. so the other night my oldest, AJ, was in bed and I noticed he was sitting up in the corner of the bed.  I went in there, rather aggravated that he was still up, and told him to lie down and that it was bed time.  He just sat there with this so sad look upon his face.  When I asked him what his problem was, yes, I actually said What is your problem? He said,"A kid at school didn't respect me today!" I was at first taken a back by his words and then I asked him what he meant.  He proceeded to tell me the story of how some kid told him to do something and he said no and then the kid pushed him down on the ground and then my son said he cried.  And now, in front of me, I could see the tears welling up in his eyes again.  GRR!!!! My blood was boiling.  i was trying hard to be the calm mom.  I was trying to be rational and to think of what would be appropriate to tell him in this situation.  Well, I should have thought a bit longer because I blurted out that he should have gotten up and kneed the SOB in the balls!!!!! And my son without blinking an eye at my words told me that he would have gotten in trouble.  Now, I should have stopped right there and told my son, your right, you need to do what is right.  But I didn't.  I told my son that is any one EVER bothers him in any sort of way to stand up for himself.  I told him that nobody should be picking him and if anyone EVER gets physical or puts their hands on him, he needs to , as I put it, "pound them!" I told him to beat the daylights out of anyone that bothers him.  Now looking back I realize I probably should have been a bit clearer.  After all, I don't want him to punch the lights out of someone who may be tapping his shoulder to ask for a pencil. I went on to tell AJ that if he ever gets in trouble for standing up for himself, I will never, ever be upset with him and he will never under any circumstances be punished for standing up for himself.  Oohhhhh I so wish I could have gone up to that school the very next day and confronted the jerk myself because I would have had a few choice words for the punk and I am sure that I would have been the one ending up in the principles office!