Captain McAuliffe's blood test was negative. Not rumour not urban legend. Fact.
OK. Said captain must have had a certain confidence concerning his level of alcohol consumption, if his test returned a negative result within *Norwegian* limits. In other words, he must have known he hadn't drunk significantly if at all prior to reporting.
So why resign? It seems no-one can say just now. Wasn't there a first officer & cabin crew involved in the Oslo case also? What were their blood test results? Is it just barely concievable that it's a case of knowingly turning a blind eye to other crew members drinking? It's an old dilema, best answered (in the short term) by the old answer: 'call in sick NOW... (unstated: or else)'.
R1