And with the Euro being explicitly set up by other countries with the intention of challenging the USD as a global reserve currency without the US so much as wagging a finger at them, it's a little hard to believe that the "real" reason a US administration dominated by neoconservative hawks resumed a decade-old conflict with an outspoken enemy in a strategically important region full of oil at a time the country was obsessed with fighting sponsors of terrorism was the relatively insignificant decision to accept Euros for some types of international payment...

The best you could say about that theory is that it's confusing cause and effect. Other nations which have been hostile to and sanctioned by the US for some time also shifted from dollars to Euros.