[EricH]

Originally Posted by DominickC

There is no rule prohibiting 2v1 defense, or 3v1 defense for that matter. The only rules which must be observed are pinning and contact within frame perimeter.

Not quite. The "Blockade" rule specifies that two or more robots cannot work together to affect the flow of the game, which flow affectation is apparently left to the proverbial reasonably astute observer to determine. (G25, in case you're wondering.)

So, if a 2v1 or 3v1 is found to stop the flow of the match, it is a Technical Foul.

(I make no judgement as to whether the call in question would be correct given the situation. I'm not a ref.)