People have misfired by claiming they "smelled alcohol on a person's breath" when it was ketones from a fat-and-protein intensive diet, back when that was very fashionable ("South Beach Diet"). Accurate testing showed no alcohol in the person's breath or blood. I recall one such incident involved a pilot.
In this case, with a Police alcohol meter showing them far over the limit, eyewitness evidence they had been drinking within the legal time limit for flying, and an admission of guilt, I think we're quite far from conviction based on a cheap-o car breathalyser interlock. On the other hand, clearly a pilot should not suffer adverse consequences only on the basis of a simple device such as those on a car which lack good control of their maintenance, calibration, usage circumstances, etc.