It wasn't classless, it was marketing. No one wants their competitors poaching their clients but in business you deal with it. That said, the same thought went through my mind, I wonder if it's related.
Most of their competitors are in the same situation they are in.
Being the first one to torpedo the other ship and not expecting someone to get upset or God forbid do something awful in return is naive.
I think there is a difference in poaching your competitor's customers and claiming they are "no good".