Evidence, as far as I know, of recent alcohol consumption, is taken from blood level, not muscle tissue.
I can well imagine in an accident like this, that when they finally find and identify the body of the pilot, there is not a lot of blood left to sample.
Heck, under 17.3G the guy may have started bleeding from ruptured vessels in his legs even before the impact. Anyone knows in more detail what happens in the human body under, say, more than 15G? All I have experience with is 6G.