This is just not true, and borders on denial of Nazi atrocities. Nazi apologia will not be tolerated in these comments.
As for why this is incorrect:
Even the most authoritarian SPD in the game doesn’t come close to the Nazis, even apart from the massive factor of antisemitism. Even the most radical SPD does not use the Reichsbanner to launch a coup or intimidate voters during elections, as the Nazis did in 1933, much less assassinate opposition leaders (many SPD and KPD leaders who didn’t flee were murdered by the SA after March 1933, and many more died in the concentration camps). It is not possible to ban the NSDAP, much less the center-right opposition (the Nazis banned every non-NSDAP party not long after taking power). Chancellor-President Braun isn’t really doing anything that presidents Ebert or Hindenberg had not done, and the unity of the head of government and head of state makes the position akin to an American president. Even the most anti-democratic route in the game, cancelling elections under an emergency government, is implied to be temporary, with the promise of new elections in the future. Banning the paramilitaries was done IRL because they were murdering people and planning to violently overthrow the government (and had in fact tried to do so previously), and the bans against the SA were largely ineffective because much of the judiciary and bureaucracy were also anti-democracy. In this environment, removing the anti-democratic parts of the government apparatus would be eminently justifiable for any party interested in preserving democracy.
Government spending to boost the economy was done by every somewhat successful government during the Great Depression, authoritarian or democratic. Hitler did it, but so did Roosevelt and Léon Blum and Per Albin Hansson. The Nazis coupled it with anti-labor and anti-union policies, which went against the core of social democracy. Not to mention the SPD’s support for women’s rights and the rights of sexual minorities, and its internationalism and anti-militarism made for radical contrasts with the NSDAP.
In fairness, there was cross-pollination in policies and politics between the SPD, KPD, and NSDAP. The NSDAP economic plan was in part inspired by the SPD’s WTB-plan, and they appropriated socialist and communist slogans. And the Iron Front was set up in direct response to Nazi and Communist organizing methods, and consciously adopted an emotional and symbolic rhetorical style like the extremist parties. But the actual substance was entirely different.
Finally, there are many paths to “winning” in the game that do not rely on anything akin to authoritarianism. It is quite possible to succeed without militarizing the Reichsbanner and without using police powers or emergency government.
Anyway, anything else like this will be banned from the comments.