and you are the man to debunk his personal findings + theories?
show us your qualifications 
Scientific/physiological facts are just that, facts. Would you dispute this?
How can a natural build new muscle tissue and lose fast whilst having a continuous caloric deficit? The answer is, he can't. To build new muscle tissue one needs a positive calorie balance, which corresponds to a positive nitrogen retention.
It could be that the gentleman was using hgh or trenbolone whilst on a diet; with these hormones it IS possible (or so I am told) to build muscle AND lose fat.