I'm sure they didn't get a code word and a dead-man's release.
You may have read by now the official lie about this treatment, which is that it “simulates” the feeling of drowning. This is not the case. You feel that you are drowning because you are drowning—or, rather, being drowned, albeit slowly and under controlled conditions and at the mercy (or otherwise) of those who are applying the pressure. The “board” is the instrument, not the method. You are not being boarded. You are being watered.
He mentions the SERE school (Survival, Escape, Resistance and Evasion) and how some of the members of the team that put him through the waterboarding experience were trained in it. I was an OPFOR (opposing forces) team member for a SERE school in Germany back in the 1990s.
My role was mostly in the Evasion part as the one the "students" needed to evade. We caught every single one (some more easily than others), but it was the Resistance part that really put those guys through hell. I chased these guys for days on the Bavarian countryside just before winter, so there were some freezing temperatures at night and snow here and there. Lots of cold, wet weather. Some of the guys we caught were suffering early stages of hypothermia, so they were glad to get caught (they had a river crossing to accomplish). My team caught up to a Brit and a Dane just as one of them was starting to have some serious problems with his feet.
I met up with the Brit for beer after
the course was done and he said he would have taken the cold wet Evasion over the Resistance stage any day. This part took place in a basement and we were racked in the attic of the barracks which had four floors. Even still, we could occasionally hear the noise of the speakers playing shrill sirens, tones, and crying babies. They had to go through the waterboarding and other tortures in order to learn techniques to deal with that sort of thing in the event of capture.
It would seem that someone thought it might be useful to employ as a torture on our own enemies.