Lots of ways to work around this. The CA legislature has issue at least one carve-out on this already, for security guards so they can eat lunch on the premises and still be "on call" in the event of an alarm. FA's are similar. Pilots are a little harder, because while an FA can be relieved of all except emergency duty, the PM needs to always monitor. But sanity has to prevail, if not in SMF then Congress can fix it... federal law can simply specify that state labor law doesn't apply to crew operating a flight.