I don’t know about the specifics of this case, but I don’t doubt that both parties do a bit of gerrymandering. I like to see it called out when it happens.
That said, I would think that this sort of thing would usually result in pretty unanimous decisions. I mean, real gerrymandering is usually pretty obvious once you shed light on it.
There is that, usually as a compromise, but often resulting in a racial factor. I think, from direct experience, that some gerrymandering is determined by partisan voting statistics; making some districts GOP and some DEM.