This says more about their qualifications to discuss public policy and labor relations than it says about unions. To pick just one obvious example, UPS is unionized -- and the company made more than $3 billion last year. That's "billion" with a "b," and those are profits, not revenues.
Oh, what the heck, let's take one more example. GE is one of the world's largest companies; in 2006, its revenues were greater than the gross domestic products of 80 percednt of UN nations. The company made more than $18 billion in 2008 -- again, billion with a b, and again, those are profits, not revenue. All that despite (or, perhaps, because of) the fact that 13 different unions represent GE workers.
Oh, and GE owns NBC-Universal, which owns MSNBC, which pays Joe Scarborough a handsome salary (and the unionized workers who help get his show on the air considerably less.)