He’s not very socialist, no. But based on your take that socialists on the west are imperialist simply for existing within an imperialist nation, something tells me you think anyone who’s the enemy of the USA must be great. (Do correct me). And that usually ends up being tankies.
He’s been outspoken on the genocide in Gaza, at least. Which is one of the USA’s proxy imperialist projects.
USA, Russia, China, they’re all terrible in their own way. We don’t get to choose where we’re born.
I’m a socialist (edit: not a “democratic socialist”, like actually a socialist who wants revolution and institution of a worker controlled society) in Australia. Am I okay with imperialism too because of Australia’s actions?
In conclusion, Mamdani isn’t gonna bring about socialism, but he’s certainly not as bad as you’re describing (that I can tell, so far).
Be careful what you wish for. The only revolution you want to have is lead by the working class (the vast majority), bringing everyone else along, in my opinion.