If this is true,

I'm not sure what could be unbelievable about this. The date of the last snowfall in NYC is pretty easy to track down, and you could pretty easily find the place on Street View and see if it matches the photo. This photo was taken from the crosswalk across Park Ave at 70th. Facing southwest, incidentally.

About the only thing you can't easily confirm in the photo is the date it was taken, but looking at the dirt level on the snowbanks and the state of the melt/thaw cycle of the slush on the road, I'd say it's easily been a week since the snow in that photo fell. So even if it wasn't taken after this current snowstorm (which would be a weird thing to lie about), it's certainly plausible that it was taken a week or so after some snowstorm.

I'm not the OP (I don't even live in NYC). It took me about ninety seconds to figure all of that out.

proves a ton about the new Mayor selling out.

He's made remarkable progress, actually. Every news article about him is something along the lines of "Mamdani fulfills another two campaign promises before lunch." It's been pretty remarkable to watch. Again, I'm not a New Yorker, so all of this is just the news that's made it to me; the reality may well be even greater.

New York City is huge, though, with a lot of problems; and he's been in office for five weeks (one of which seems to have been fully dominated by a state of emergency). You can't fix everything in a city of that size even in four years, let alone five weeks. And it seems like most of the problems he's been working on so far have been more directly impactful to people's survival; stuff that's lower on Maslow's hierarchy.

If he puts up a few months with no meaningful wins, or does something clearly corrupt, then maybe I'll start considering him a sellout. But in the meantime, I'd say he's earned a significant amount of goodwill.