His fight isn't going to be over once he's mayor. The capitalists won't just roll over. He could be planning on using some of those volunteers in his team instead of consultanting firms. Outisde, they'll probably keep pushing public opinion for his policies. Its hard to tell exactly what he'll need from them now.
None of this is an actual hard guarantee that he won't sell out and go turncoat if that's what you're wondering about. His antizionism is really the guarantee of that. Either he drops that or NYC bourgeoisie drops Zionism before he turncoats. Otherwise it would be the most dramatic case of political suicide.
IDK why you're being so rage baity. Its easy to avoid flatpaks if you dont like them. Only thing I've ever found as an obstacle was adding the binaries to my PATH so I can launch it with dmenu_run. Otherwise my package manager works well enough.
Bonus points: Write a PKGBUILD that installs flatpaks to /opt and symlink out binaries as needed.