One poll of this moment in time, sure. We've had two polls in February that also showed him in the mid 50s approval. I see no reason why this poll "wrong" because you don't like it. We'll get a few more polls in the next couple weeks and I'm sure you'll find another excuse why those should be ignored as well.The ABC poll is not an indicator of anything. Go read Nate Silver's take on why a singular poll means absolutely fuck all at this moment.
In response to your edit above, only proves my point. Trump's approval rating remains largely unchanged, even in the wake of this crisis. If the American people disapproved of his handling, we should've seen it dip.