Just a point from the OP - he never said he was low on air. In fact, he said he did not check his gauge and just had a feeling:
I could feel the air getting harder to breath and I panic
I know he has not expressed himself very clearly about the event, but it is possible he was not even low on air, but just panicked (due to depth, viz, temp, or any other issue). He also swam to the surface "as fast as he could" and spit his reg
despite having just run skills and doing a reg recovery (or whatever skill he was doing by "making an 'ahhh' sound"- I'm assuming it was not a CESA). He didn't mention having any difficulty with the skills, so there is no evidence that the instructor (or DM - hard to tell) should have had any indication that he would have any issues.
yhike admits he knew what he did was wrong according to training standards. He also does not want to name the dive center:
I will not name the dive center I have nothing but good things to say about the Dive Center and would not want to ruin their name.
Yet their apparent lack of training almost led to a tragic incident. Does that seem consistent to you?
Our assumption is that his performance reflects his level of training, which could very well be the case, but it is also just as possible that he just didn't perform the same way he did during his previous instruction sessions. Is it fair to assume that someone will always perform up to the level of their proficiency demonstrated while being instructed (not that they
should, but that they will)? Our first instinct seems to be to blame the instruction.