That’s a strong GMs opinion and who is going to argue with him? Even we amateurs know it’s a bad move. Still, there is no direct refutation to this stupid looking defense and it will take your opponent out of any preparation he might have. One thing I have discovered is that it usually morphs into a pattern that resembles a ‘real’ opening. For example, one of my games (I was White) opened 1.a4 e5 2.e4 Nf6 3.Nc3 Bb4 4.Bc4 0–0 5.Nd5 which sort of resembles a Ruy Lopez Bird Defense with the colors reversed.
In the following game 1...a4 lead to a pretty boring position and we agreed to a draw in 28 moves. Sometimes known as the Corn Stalk Defense, US Master Preston Ware played it in eleven tournament games from 1880 to 1882, winning four and losing seven, but that likely speaks to Ware’s ability, not the defense.