I disagree completely. Visa sponsored the event - why would they want competitors there? When the average person sees that his or her Mastercard is not accepted, I don't think the first response is "damn you, Visa!" Just like, when I see an AMEX card isn't accepted, I don't say "Damn you Visa and Mastercard for offering lower rates!" The image that Visa is trying to promote is that they're the most commonly accepted…
WOW! It is totally not offensive, positive and good for MC public image. They must be some marketing wizards or something!
Either that, or Visa people are morons.
* Edit: misprint