Yes, methane is a greenhosue gas. The amount that would have been released would have been negligible on a global scale, and it certainly wouldn't have "polluted the area" as phi1997 stated.
The debris apparently also affected hundreds of acres of land, including damaging the habitats of protected wildlife.
It "affects" hundreds of acres of land in the sense that it is part of it. It's gravel, essentially. Gravel on a beach.
Do you have any evidence that it damaged the habitats of protected wildlife? The FAA has been conducting environmental assessments and they have the authority to shut down operations if they think there's a danger. They haven't.
Musk chose to forgo launchpad frame trenches which are historically used
The water table is just a few meters below the surface of the ground. Building a flame trench is impractical. It would also be far more environmentally disruptive. And just because it's "historically" used doesn't mean it's the best approach. Rockets are historically disposable, the whole point of Starship is to break with historical traditions.
but didn’t have his water-cooled steel plate idea ready,
Indeed. As I explicitly said above:
they already knew they would need to rebuild it with a more robust design but figured it would survive one test launch so they delayed the planned renovations until after the launch.
If they'd decided to delay launching until they had the steel plates in place they'd only just now be getting ready to do their first test launch rather than their second.
