I thought I might chime in. The beauty, the unexpected genius of reserve green slips in fact, is that they essentially function as a GSWC. But....they are merely defined as a GS in the trip coverage ladder! This may be the ONLY place in the contract where a reserve vs regular line holder are not on a separate coverage step. The trip coverage ladder merely states "green slip" and NOT "regular green slip" followed several steps later by "reserve green slip."
In hindsight it was a monumental oversight on the company's part many years ago. But many years ago, green slips were a far rarer occurrence, senior guys got two GS before a junior guy got one (a bad rule that we fixed in C2K) and reserve was so awful that the idea of bidding reserve on purpose was hard to imagine. So reserve green slips were very rare.
So now the company is seeing all these PB days causing some disruptions. So be it. I am guessing that the company would love to change the reserve GS rules, but I don't see that ever making it into a TA. That would be a "one issue NO vote" for many.