Jesus Christ this is infuriating. This is the last thing I'm gonna say before I delete this whole thread in the morning and hope to forget I ever had to endure this. What I'm saying is:
Bloomberg is well known as being an advocate for local govt. taking on climate change, independent of his charitable giving
Therefore, it is an entirely reasonable conclusion to make that the endorsements were not influenced by his funding.
Even in the grants that he's made to mayors, those funds are part of an extremely complex network that means the cities don't end up actually getting all that much of the grant.
Therefore, it's even more likely that the endorsements were due to Bloomberg's advocacy rather than his funding, as the primary benefit to the city is via connections rather than direct monetary gain.
So, Saying that Bloomberg is buying endorsements is a. the less likely option b. Is actually insulting to the mayors by removing their agency and c. Based on the least generous interpretation possible based on pure speculation.