Germany has a BAC threshold where acting stupid while being slightly tipsy is considered worse than acting stupid while being perfectly sober and that is indeed quite low (0.3). This entry level threshold does not distinguish between car and bike at all (pedestrians are fine). That level basically means "go for it, but at your own risk, and if someone else fucks up, you are partially responsible because might very well have have saved them if you had not been drinking".
But the "folk wisdom" of drivers completely ignores that threshold and only considers the next stage relevant (BAC 0.5+, used to be 0.8) and this only applies to motor vehicles. For cyclists, the next threshold does not happen before BAC 1.6. I suppose that wouldn't exactly be allowed in the UK either?
