Is disrupting opposite faction players fishing a bannable offense?

Today I saw an Alliance player fishing in Orgrimmar. He was well geared, while I was wearing a terrible PvE set. I couldn't fight him, and he couldn't attack me either because PvP was turned off.

However, I decided to troll him a little by moving my mounted character on top of his fishing bobber so he couldn't click it.

Later, I received some threatening messages saying that I would be reported for disrupting gameplay.

I can partly understand why this could be considered disruptive if it was done to a player from my own faction, but what about a player from the opposite faction? I was too weak to fight him in combat, but at least I stopped him from fishing up the Old Crafty, which I consider a success.

Don't think that counts as disruptive gameplay.