This is nothing more than a publicity stunt for Pink Taco in Scottsdale. It's being talked about on the radio today.
First of all, it makes no sense to advertise for Morton's/Pink Taco with stadium naming rights. Pink Taco only has 2 locations and only 1 in an NFL city.
Morton's is nationwide, but advertising on an NFL stadium is the wrong demographic. Beer/Airlines/Fedex work. But they are not hitting their target market to advertise a place where a dinner for 2 costs $170 with the average NFL viewer.
I'm sorry but $3M is just too low. Houston receives $10M dollars/year for naming rights, and this stadium will host Super Bowls, the Fiesta Bowl (with a national championship every 4-5 years) and possibly an NCAA final four. The Bidwills are not going to settle for $3M/year.