Aren't Unions a Step Backwards for Marxists?

A poll commissioned by the AFL-CIO has found that full-time faculty members at public universities that aren't unionized would be interested in a union or something like it. LINK.

We would have thought all full-time professors at public universities were already unionized. Our view has probably been skewed from attending school in Ann Arbor, which is on the outskirts of the UAW stronghold of Detroit.

The article, by the way, also makes this startling observation:

Support for the idea of creating a union also depends on professors' success without one. Professors on the tenure track but without tenure are more likely than those with tenure to favor a union (45 percent to 34 percent). And those who aren't satisfied with their jobs are more likely to support a union than are those who are satisfied (55 percent to 31 percent).