Doesn't it seem far more likely to be indifference to a negligible market share than ignorance of Opera's existence? It's not worth their money to spend any amount of time making a custom error for "Your browser is new, but we don't support it anyway" separate from "Your browser is old and we don't support it" when 99.9% of the people seeing the message are in the latter category.
I was referring specifically to khet's statement I quoted. What is Myspace "standing up for" here?
What does showing a message "Our superpowers have detected you're using an outdated browser. That must mean: a - You don't use the Internet very often. b - You're at your parents' place on the PC they bought in 1996. c - You work for the government or a big corporation." to users using a browser released in the past month stand up for, other than ignorance?