How have they insulted them? What is inaccurate?

The Iron Front chiefly opposed the Sturmabteilung (SA) wing of the Nazi Party and the Antifaschistische Aktion wing of the Communist Party of Germany.[1] Formally independent, it was intimately associated with the Social Democratic Party of Germany (SPD). The Three Arrows, originally designed for the Iron Front, became a well-known social democratic symbol representing resistance against monarchism, Nazism, and communism during the parliamentary elections in November 1932. The Three Arrows were later adopted by the SPD itself.[2]

The Iron Front was formed on 16 December 1931 in the Weimar Republic by the Social Democratic Party (SPD), along with the Allgemeiner Deutscher Gewerkschaftsbund (ADGB), the Reichsbanner Schwarz-Rot-Gold, and workers’ sport clubs.[3] The Iron Front chiefly opposed the paramilitary organisations of both the fascist National Socialist German Workers Party (NSDAP), i.e. the Nazi Party, and the Communist Party of Germany (KPD).

The Iron Front was regarded as an anti-communist and “social fascist terror organisation” by the KPD, who regarded the SPD as their main adversary.[5] In response to the formation of the Iron Front, the KPD founded its own activist wing, Antifaschistische Aktion (Antifa), which opposed the social democrat SPD and the fascist NSDAP.[6]

On January 30, 1933, the day Hitler was appointed Chancellor, the KPD asked the Iron Front, the SPD, the general trade union association ADGB and their organisations, and the Reichsbanner Schwarz-Rot-Gold to declare a general strike against Hitler. The Iron Front declined, issued a call on February 2 to “all comrades of the Reichsbanner and the Iron Front”, warning against participating in “wild actions organised by irresponsible people”, and exhorted members to “turn all Iron Front events into powerful rallies for freedom”.

Later the SPD is involved in their arrest. What’s “illogical” or not factual here?