Q. Is the Thin White Duke who remixed Viva La Vida in any way associated with David Bowie?

Certainly David Bowie used that moniker before Stuart Price (also a.k.a Thin White Duke) began using it for his remixes. That's where their connection with the name ends.
FYI David Bowie was the curator/director of the Meltdown Festival back in 2002. In this role he chose Coldplay as one of the performers.