It's interesting as the unique tail section was actually touted as a "safety feature" by the company. I'm not necessarily saying it can't be the case, but like any feature, even a safety feature (see: exploding airbags), defects or improper use can cause more harm than in it's absence.
An improperly implemented safety feature (emergency ballast blow system) contributed to the loss of USS Thresher... In the same way, the Apollo 1 crew died (in part) because of a system (a well locked down hatch) that had been installed to prevent a repeat of an earlier accident. (Which, by morbid coincidence, one of the crew had been involved in.)
It's a bit strange, as it seems like such a fundamental error - not some obscure feature that could be overlooked. What pilot would say to himself "Hey, I know I'm supposed to unlock the tail at time X, but what the hell, why not just do it now?" It seems really strange that they wouldn't have precise procedures for this, since it's such a critical part of the entire design.
It's not so much that, as the pilot appears to have become confused due to a) the simulator not properly conditioning them, b) lack of recent and overall experience with the vehicle, and c) high cockpit workload at that point in the flight compounding a) and b). At least that's how I read the report. (The abstract and summary of which is not clearly linked of the summary or TFA but which can be found here.)
From my experience in the Navy, I can say that obtaining those reflexes isn't easy, and neither is maintaining them (regardless of experience).