I think the Schneidermann resignation was the turning point that gave the good guys the leverage. Rudy has just come on board, so I'm thinking his guys inside saw the chance to get stuff out to the right people.
I think that had the effect of putting the brakes on Weissman. Speculating that an attack on Weissman would have looked like fucking with an ongoing investigation, so they took our Schneidermann as a warning. Sex scandals about Mueller surfaced about that time, too.
TL;DR NYC good guys got leverage with Rudy on board and cut Mueller's legs out. Hoisted him on his own petard.