I don't see the problem with this argument. Seattle has 3 professional teams and lots of tourism. Losing one team is not going to have as great of an impact as say the Packers moving from Green Bay would. A professional team is going to make far more of an impact on a city with one or no professional sports than it will on a city with several.

It's kinda like the Dodgers didn't hurt New York too bad financially when they moved as much as they helped Los Angeles. The Dodgers helped LA's economy and image far more than it hurt NY. Remember LA wasn't the same city in the 50s that it is now.