I saw the movie this past weekend. My son teenage son HAD to see it. I figured it was a bonding experience for my son and I. It was very weak on plot and basically one long chase scene. I found it hard to believe it was directed by the same guy that made the first three. Those movies actually had a plot. This was just a vehicle for special effects. My son loved the movie(16 year old). I thought it was horrible.
I did not really pick up on the pro homo message. Just the fact that all men are bad and women are good. What I did not understand is if the women dominated society by the chicks on bikes was so great, why did their lush Greenland(or whatever they called it)turn into a marshy wasteland with those things walking on stilts? Again no plot.
The “Green Place” essentially died as part of the ongoing natural catastrophe resulting from the war. It’s more subtle in this movie than it was in Thunderdome, but there was at least a limited nuclear exchange. Recall that once the main characters met up with the tribe of old women, they faced a 160 day ride across the Great Salt plain. The implication is that the oceans are gone, or nearly so. The planet is dying, and the Green Place is a victim of that. I recommend you go to tvtropes.org, which has a fair amount of info on the movie, including some background that came out in other materials.