That's a pretty uninformed and superficial analysis of what SCOTUS decided.  Besides, if it's OK for unions to advocate, and spend member's money on elections and candidates...putting members' $$ towards candidates the members may not support, why shouldn't ANY entity have the same benefit.  As to where in the Constitution is it allowed....where in the Constitution is it NOT allowed?  SCOTUS did NOT make "corporations" into "people."  Any entity has the right to free speech.  Do we restrict the "freedom of the Press" to Sidebills and Newspapers only?  I'm thinking the press is "free" in any medium.  Remember, the Constitution is a LIMITING document on the power and authority of the federal government.  If it's NOT in the Constitution, see Amendment 10 (as THAT'S who the power and authority rests with.)