This is what DALPA is telling it's pilots.

A regular line pilot on days off and a reserve pilot on X-days or payback (PB) days are both considered to be at rest. However, a pilot cannot accept an assignment for a rotation that begins with a flight duty period unless that pilot deems himself fit for duty per FAR 117.5.

A pilot on days off is permitted under the FAR to volunteer for additional flying (WS, GS, YS). That means it is legal for a regular line pilot and for a reserve pilot on X-days or PB days to accept an award or an inverse assignment for additional flying. In those cases, the pilot is essentially saying that he has met the requirements of FAR 117.5 and that he is fit for duty for the awarded or assigned flying. If the pilot cannot meet those requirements, he cannot accept the rotation, and must inform the company. By signing the release, each pilot is certifying that he is fit for duty for that flight.


That being said, this would only apply to a voluntary assignment. So wrapping back around to the whole junior man thing, one does not HAVE to accept the assignment if it's less than 10 hours. They can't make you. But it is legal for one to accept.