The level of recorded ethanol in muscle tissue, is based on the water content. Complicated process, but the ethanol is trapped in the blood water, which soaks into the muscle tissue. Generally however, this level disipates after 90 minutes. It is used as a back up to breath testing, however, multiple variables are at play in this process, and every individual is different.
Because of wide inter-and intra-individual variations in the absorption rate of alcohol, attempting to calculation a person’s BAC based on information about the amount of alcohol consumed is not recommended
Back to the incident, agreed that a variety of elements are at play here, and it is right that ALL causes be fully investigated, reported, and dealt with. I think the FAA, NTSB, are doing this.