I think it's safe to say Martin Luther King, Jr., was a 20th Century American Liberal; for, he believed that the U.S.'s highest political priority should be equality, and that's what defines someone as a 20th Century American Liberal. So, Martin Luther King, Jr., probably thought that Capitalism was problematic, for he either thought that or he wasn't a liberal; and we've already established that he was a liberal.

But he wasn't a Communist. Because he believed that individuals should be allowed to own private property, and noone who believes that individuals should be allowed to own private property is a Communist. So, given that King was not a Communist, the F.B.I.'s J. Edgar Hoover should not have publicly portrayed King as a Communist. Since Hoover should have done it only if King was a Communist.