....I mean, we're talking about forcing a player to forfeit varsity eligibility to play in a JV game.
No way, no how does this fit the spirit of a "quarter played" rule. Players should be used at multiple levels in the manner the coaching staff sees fit. If a coach tells me that the player is unavailable because s/he's playing in the varsity contest, that's good enough for me even if s/he's still sitting on the bench in uniform.
The other coach arguing and trying to get the player to burn eligibility? To me, that's unsporting.
In my opinion, the right way to handle this is to get the ball back into play right away and not give the other coach the time to complain about it.
And since there's a powerplay, remember that the team with four players can ice the puck whenever they want
Rich