The environmentalist themes continue outside Midgar. The planet-draining presentation you get at Cosmo Canyon is about as on the nose as it can get. The weapons are planetary defenses, though that's endgame content outside of the incident at Junon. (Does Sephiroth hijack them? I forget.) Sephiroth is a product of "science gone too far (insert ghostly wailing)" and his mental break after finding out that he's an alien test tube baby is rings in a different, more pressing apocalypse. The planet's restored life energy is what ends up stopping that one by buoying the meteor. The ending shows Midgar (the industrial dystopia) overgrown by lush vegetation as Red XIII and descendants run about (nature wins).
Yeah, the game stops literally saying "boundless exploitation bad, m'kay" as it shifts to Cloud finding himself and his personal conflict with Sephiroth takes center stage. It is a game for teens after all. The environmentalist themes are there though.
It's not a 'political game', whatever that means, but it's the most overtly political of that era of FF.