If they had video footage of someone waiting in the parking lot, they'd have released that and they wouldn't have sought a search warrant for PF's property and wasted tax dollars on a search of his property and vehicles.
I will say that there is some connection between the shopping trip, the phone call to her mother and the recipe KB asked for. I'm not sure what it is, but in one of the interviews CB was asked for more detail about what the recipe was, she hesitated and then repeated that KB had called asking about a recipe and refused to go into any more detail. Since you normally shop for things for a recipe, it would stand to reason that whatever KB bought at safeway was for that recipe. But why be coy about it?