in a recent supreme court decision have gained the right to pay as much money in secret to support whichever candidate for any office anywhere they wish.

...funny how "we" the people cant do that huh?
It sounds like you have misunderstood the Citizens United ruling - which does indeed allow groups of people (incorporated or not) to spend their money to endorse or criticise candidates, in the same way that the individuals concerned can. It does not allow that to be done "in secret" - the statutory requirement to identify those paying for such broadcasts remains - nor does it allow them to do anything individuals cannot. In particular, corporations still can't give money to candidates, unlike individual people: all they can do is express their opinions publicly.

The alternative, that releasing or promoting a film critical of a candidate would be illegal because that candidate is running for office, seems absurd for any developed country, let alone one professing to support freedom of speech. Libel laws permitting, I'm free to post rants on my blog about what an evil baby-eating monster Bill Gates is for pushing Windows on us all; I could club together with a thousand other Linux or Mac users to run that rant on the pages of the NY Times or as a Superbowl ad ... but suddenly, if Gates decides to run for Senator or President, that would be illegal - you really think that's right?