The way I read the first post it was mearly asking a procedure question not actually advocating flying after diving.
Divers don't normally survive to be technical diving instructors if they have a lazy attitude to risk managment. In fact is some ways the technical diving risk managment is far more conservative than our fuel contingency. It's normal to surface with 33% of your gas left to cover cock ups.
So I think that last post was a bit harsh. I presume the question was asked to further the education of Dave's students who will not be thick or gash when it comes to thier own risk managment.
The problem occurs with the ever increasing PADI open water divers who do a bit of theory, dive maybe every couple of years in warm water with thier hands held by some PADI divemaster. Most will not think twice about doing a couple of 20m dives then going out on the lash all night to jump on a plane 18 hours after surfacing.
The Scottish SubAqua club and it's younger cousin the British SubAqua club have completly different training philosophy's compared to PADI. decompression theory gets hammered into the student if they like it or not. If you get onto daves level in tech diving it requires no small amount of degree level maths to understand it properly.
Link below is on bubble theory
Deep Ocean Diving - Science, technology and medicine related to scuba diving
And another with comments on the most common model used for working out the no fly time.
Saturation effects in diving, the Model <font face="helvetica">ZH-L16</font>, operation of dive computers