The act in BJCCs posting applies to all Aviation workers, so Flight Crew, Check In Agents, Ops Staff ...... everyone (this is based on information sent out by the Manchester police in 2003 to all airlines from MAN). So for example driving to the airport maybe ok under road traffic rules but you can be arrested at a lower limit if your arriving at the airport for work. The US regulations don't mean anything in this case, a pilot has to conform to the state rules where they are at any time, nothing to do with registration, company rules etc. (remember the BA pilot at OSL). The 12 hour rule is meaningless and should never be used, generally being sober and blood free of alcohol 12 hours before is a more realisitic rule.
As for the discussion on positioning crew, read your Ops Manuals - most refer to 'on duty', and the normal definition of 'on duty' includes positioning, even on a passenger ticket and not in uniform, after all you have minimum rest calculated pre and post positioning in accordance with the normal duty rules. Also Ops Manuals often state you must be fit, rested etc for the full limits of a duty, so even if your positioning you should be in a state to perform duties if required to the legal limits as this is 'duty'. In the main Ops Manuals are not applied in this way and the 'normal SOP' is not to follow this, but if you were ever in court I'm sure they would read the manual and not accept common practice.