Either way there are a ton of non-financial benefits here, this is great to see.
Those districts are in the same atmosphere as the rest of us.
If it's bad to use them to burn diesel in LA, it's bad to use them to burn diesel anywhere.
Not every environmental policy is about stopping the planet from warming. Sometimes it is about stopping our kids from breathing exhaust and waters from getting filled with microplastic.
So while it would be best to stop burning fossil fuels entirely, we benefit if LA paves the way on electric buses. If they have to defer to cost by selling old stock to those who wouldn't be buying electric anyway, it's still a net win. And slightly better if the other pollution they still make doesn't produce the same concentration it does in Los Angeles.
If the entire planet experiences catastrophe and there is a mass extinction and agricultural collapse, I feel like this is a distinction without a difference.
Then again, perhaps you are right, as it appears we are imminently headed toward this future even if every diesel engine on the planet stopped operating today.