You're partly correct.
McCain-Feingold needed to go.
That could have been done on much narrower grounds than granting full individual protection for political speech to entities that exist only on paper and with the sole purpose of commerce. Or, in the case of unions, that exist only on paper and for the sole purpose of collective bargaining. These are organizations with zero, zip, nada political responsibility, accountability or purpose.
Don't get me wrong, I'm not anti-corporation. And CU is as big a threat to the integrity of the corporate structure as it is anything else, by weakening the theoretical legal structure of the corporate veil.
But there is an inherent lack of responsibility and accountability in the corporate structure that doesn't exist for individuals. The fictitious entity can be created by anyone, anywhere in the world with any agenda, but as its own "person" on paper as long as there is a PO Box and a piece of paper filed in a State somewhere in the US, it's an American "citizen" for all purposes under CU and now has access to engage in the political process to its heart's content - without any accountability whatsoever. A corporation gets in trouble? No problem, the principals can merely wind it up, get a new charter and voila! They have a clean, new "person" with no record. And the principals are protected by the corporate veil - almost completely - for any accountability for the actions they take on behalf of this fictitious person.
Full rights, no responsibility. Way to go, Supremies!