That presumes that (A) either one was interested [probably not, but who knows given that specific situation] and (B) either one actually had a shot at the Thrashers [by all accounts, no - it was intentionally kept quiet as long as possible to avoid lawsuits and delays]. But why stop there? Why couldn't it have been Milwaukee, or New Orleans, or any of the oft-mentioned cities that have an NHL-capable arena and no NBA team playing in it?
Again, any pro sports league can ask for whatever expansion fee it wants. It doesn't mean it's right, it doesn't mean it's grounded in reality, it doesn't mean it has to have any kind of bearing to what franchise values are for other teams - but if one someone's willing to write the check, that's all that matters.