“the argumentative content that you chose, the strategy that you chose, for that judge and for his stated philosophy, was a poor choice on your part.”
That means that the team failed to take into account the known prejudices of the debate judge, which is apparently a valid part of debate-contest strategy. In general, in a practical sense, this is true. This goes back to ancient rhetoric, wherein all the teachers insisted that the argument be designed around the known prejudices and knowledge of the audience.
The kids will learn in law school never to use an argument that exceeds the judge’s intelligence.