Anything other than zero tolerance would destroy public confidence, and that of the existing workforce.
Would it ? If so, so what ? They wouldnīt fly no more ? Unlikely....
Whilst being a teetotaler and
not a drug user myself, I donīt see this sentence to be the least bit fair. There is no way back for this guy and that is NOT okay. Give him a sentence and then - when sober for X-moths/years - allow him back. Testing is available.