There is a legally defined blood alcohol content but I haven't found anywhere a legally defined muscle alcohol content. I haven't found any studies (I'm Googling - I'm not a medical expert) which show a link between blood alcohol content and muscle alcohol content.
No it is not reliable because of the degradation of the body and other variables but hence why its all the more surprising blood analysis wasn't done. That aside the level in muscle is broadly 0.8 of that in blood.. I.e 80mg in muscle would be 100mg in blood.
Although it is impossible to say what the situation truely was in the air given the lack of data.