The shooter didn't say that. An bystander said that.
Oh yeah, the 911 caller call that said the shooter was an undercover officer. Yep, same guy. Ya think the shooter disagreed with him later?
Back to my point:
Why would anyone think the guy opening up in a supermarket parking lot was an undercover cop?
It's because many times when people call 911, they are just parroting what they heard occurred, and are just passing on bad information.