That the nazis could not increase their support without identical conditions.

Identical conditions are not a prerequisite. The nazis can tap into frustrations other than unemployment (low wages, perceived reverse discrimination, etc.).

I'm not so sure ignoring them is the best strategy. While I see the logic, the action of not showing up to oppose something can also be seen as antipathy or tacit support. Showing up makes it clear to the cameras which group has greater numbers (and raises the stakes for the wimpier nazis that may have concerns about their safety).

Let's not assume something directiinally similar could never happen here. Paradoxically, that makes conditions more favorable, not less. History tends to repeat itself on an interval that corresponds to when people have forgotten the past, or view it as too distant to be relevant.