Make no mistake Citizens United legalized bribery you just have to wink a say it's a "campaign contribution". Everyone involved knows what it really is. Unless you actually believe that the fact that politicians pass laws that are extremely favorable to firms while receiving millions from them is unrelated, if you do I have a bridge for sale.
Citizens United was not about campaign contributions. It was about whether or not a corporation could use its funds to create materials denouncing (or praising) a candidate for office.