On the Congress level, that cartoon is nonsense. The Democrats could've picked up no less than three and probably five seats if they had passed an aggressive redistricting scheme. They didn't. They just passed on incumbent-protection map so no one would ever have to go through the bother of really campaigning for reelection.. :)
Actually, it was because they didn't want it to go to a referendum, which would've happened if there weren't a supermajority (I forget how much of a supermajority) in the legislature.
The only reason for Republicans to support this redistricting initiative is on principle, because the GOP will probably lose seats if it passes, at least on the Congress level.