Citizens United was primarily about allowing leveraged discussions of such topics in the 1-2 months before Federal primary and general elections. A ban on core political speech, and since the primary season is so long, and the national conventions are just a bit more than 2 months prior to general elections....

Which is exactly why the incumbent establishment was incandescently upset that this decision stuck down part of the bipartisan McCain (Republican)-Feingold (Democrat) law.

Key there is leveraged. That takes money and organization. Citizens United was about suppressing the distribution of a film during the 2008 Democratic primary season (as clarified during the oral arguments, this extended to books). The law went so far as to prevent sending non-partisan voter's guides such as the NRA's 60 days prior to general election; "low information voters" would not seem to be viewed as a great problem by our betters.

Do you really can't talk campaign financing reform as if it was offensive content or call to violence?

I'm not sure what you're trying to say, are you referring to how I've discussed "campaign financing reform" above?