I love Seattle as a town and it's my intention to have a home there some day. That being said, I'm less interested in making sure there's a team in Seattle than making sure there's a chance for two places that have everything lined up having one. I can't see the reason to hold everything up for Seattle.
Seattle needs an arena. Key Arena is 53 years old and isn't ready for any major sports and it's not an amazing venue for concerts and other events either. Seattle is doing the Seattle thing and exhausting every single option to make sure everyone is happy with what happens, it's what they do.
However, when it all comes down to it, they need an arena no matter what. Do you want to build it, or don't you? QC and LV (and a few other cities for that matter) have arenas with no guaranteed teams, why does Seattle think it's so special that they should get a guarantee? Build the place and they're now a soft landing spot for Arizona if it's needed/expansion to 34 and maybe a NBA relocation/expansion in the future. They get rid of a half century old arena and replace it with a state of the art arena plus they get some extra space in Seattle Center in the bargain. Seems like a win win to me.