I found a piece which makes the point I was trying to make in this thread but did it much more clearly.

Under the language of this decision, foreign corporations can now spend money in American elections. And it is probably now unconstitutional to restrict foreign nationals from spending money personally.

Now most probably won’t like that outcome, and maybe the Court would be open to new laws that restrict this to some extent. But it will be difficult to craft a constitutional exception.

“The ruling affirms that corporations, like individuals, have a free-speech right to spend unlimited amounts from their general treasuries on ad campaigns that support or oppose political candidates. It’s true that foreign nationals are currently prohibited by law from making independent expenditures in U.S. elections. But that prohibition has little teeth. According to experts, it doesn’t apply to foreign-owned corporations that incorporate in the U.S., or have U.S. subsidiaries — meaning most foreign multinationals likely aren’t covered. So there’s “essentially no difference” between domestic and foreign corporations in terms of their ability to pump money into U.S. elections, says Lisa Gilbert of U.S. PIRG — a view backed by several other advocates of increased regulation.

And even if the definition of a foreign corporation were interpreted more broadly, the logic of the ruling suggests the ban may now be unconstitutional anyway. In ruling for the majority, Justice Kennedy wrote that the court’s decision did not address the issue of foreign actors — implying that the ban would remain in place. But as Justice Stevens pointed out in his dissent, the vision of free speech that the court has embraced — and the notion that corporations should be treated as individuals — could make it very difficult to support singling out foreign corporations for special restrictions. “The sweeping freedom of speech rhetoric would have applicability to foreigners,” says Edward Foley, an election-law expert at Ohio State University, who thinks the court has sent “mixed signals” on the question.”

http://tinyurl.com/yelx8g5