Can California Police Interrogate/question You Past The Scope Of A Fix-it Ticket Traffic Stop?

Buddy got pulled over for tinted front windows, him and his passenger were asked to step out of the car and questioned separately about where they were coming from and such, and when their stories "didn't line up" he was cuffed "for safety" while the officer ran a dog around the outside of his car. Now he's facing some heavy charges. The limited info I was able to google says he shouldn't have been questioned past the scope of the fix it ticket so things like where they were coming from and going shouldn't have been asked. Is this true and what would it mean for the case?

I understand that because the K9 was already with the officer that it was valid to run the dog around the car as long as it didn't extend the duration of the stop, but wouldn't the extra questioning be a violation in the same way since it went past why he was pulled over in the first place?