"the bourgeois parties... [and] the Nazis who they collaborated with," implying a distinction.
A distinction without a difference. Whether explicitly bourgeois parties or not, the Nazis and SPD were both vehemently opposed to the ideology of the KPD, and those two parties received a majority of the votes in the 1932 election.
Working class people can and did support bourgeois parties...
And do, still. By the millions, in every election. Or, at least, if not explicitly bourgeois parties, parties that are based on some form is liberal ideology, not necessarily in opposition to bourgeois interests, and that often are aggressively opposed to Marxism-Leninism.