The reason your pilot did not don his O2 mask is because the 76 (as do most modern transport a/c) satisfies para 2(i) in that the masks are quick donning type.
You literally pull the mask out of its housing and pop it over your head. When you let go of the paddles (which were grasped to remove the mask) the mask then self seals around your nose and mouth. The action takes no more than 3 seconds, a little more if the pilot wears glasses.