Corporations did not have that right until the Supreme Court ruled that they did in the Citizens case (although it may have occurred in practice prior to efforts to control election spending)...which many still dispute being a legitimate interpretation of law. If there's a change in balance on the Court, they might be inclined to revisit that decision. It's not like the Court can't and hasn't revisited controversial issues and changed the ruling.That wasn't what the ruling claimed.
Corporations have had some of the rights of persons since before the country was founded, eg, the right to sue in court.
This is because corporations are how people assemble to accomplish things.
The question becomes which rights they have or do not have, eg, the right to marry.
Political advocacy is one right they have, & spending money enables that.
Ref....
https://en.wikipedia.org/wiki/Corporate_personhood