In Bikrams new book the sit-up is taught differently.
Inhale and then do sit up, first exhale going down and then another exhale. Forehead to the knees.
Also, when looking at old pictures of Bikram, one can see many differences in poses than it is taught today.
So, it seems to be a lot of inconsistencies. Which makes things confusing, as Bikram says it is very important to try the right way.
Personally I follow Gabrielles recommendations, as it feels better and makes more sense. Maybe Bikram himself is not the best expert when it comes to anatomy and how to do poses safely. Or he learned his stuff before science discovered more about human anatomy? He is not aware of the Ayurvedic approach to exercice and beleive all sports are bad, just because he himself used convential training methods (which is bad for the body) and got hurt.
I recommend him and everyone else to read John Douillards book “Body, Mind and Sports”. It fits perfectly with Gabrielles approach to yoga.
BTW, why is this site not called Bikram Yoga Doctor?