It appears to be true. The only sports game rated higher on Metacritic for the 360 is NBA 2K12, which isn't out yet (and doesn't have many reviews). It looks like it dropped a point since that press release on PS3, which puts it in a tie with a version of The Show for highest critic rating.
Edit: Leaving the mistake in. I didn't realize NBA 2K12 had been released. I'm not much of an NBA fan.
But prior to yesterday, they could say they were the highest rated sports game of this generation.