Since Pete Seeger is a writer as well as a performer, and is person who puts his opinions into song, one can take him more seriously than one who only performs the words of others.

In film-making, the creative "pecking-order" is Writer, followed by Director, followed by Actor. Logically, one should weight their opinions accordingly; however, in practice, the order is usually reversed.

There is no reason to think that the opinions of an actor are wiser than those of a plumber, but they do have more influence.