Umm... yes? You need only one example to disprove a theory. That's how theories work.
For instance, if you can find one example to disprove Einstein's theory of relativity, you win and Einstein is an idiot. Good luck
I think that depends on the specific theory in question now doesn't it?
General Relativity proposes a theory for how the universe operates. By it's own theory if you can find an example that directly contradicts the predictions of relativity then you've found a flaw in general relativity.
Lots of questions are nowhere near so specific. Lets say I have a theory that men tend to be taller than women. Just because you find one woman taller than I am does nothing to disprove the theory because me theory only talks about tendencies.
Nobody has said all players will stay away from Arizona (or if they did they're not thinking it through). Clearly it's not true as the Coyotes continue to sign free agents. The Coyotes do have some selling features - warm year-round weather, no intrusive media. While Arizona does have a state income tax it's fairly low.
So instead the theory around Arizona is more that they will have more difficulty attracting players - in particular high-end free agents who are looking for a long-term contract.
So it's easy to see why Troy Stecher would want to sign in Arizona. It's a nice community, he knows the organization - and it's only a one year deal.
But good luck to Arizona signing someone on a long-term deal. Because of the instability around the franchise you could start playing in Arizona, but then have the team relocate to who-knows-where.