>>Should the foot fault have been called?<<
Tennis doesn't work like basketball where the contact rules are correctly judged by the advantage gained by a player initiating (even inadvertently) contact or the disadvantage it puts the contacted player in. There, the official (rightly or wrongly) decides whether the contact is a foul or a no-call.
Foot faults are an inherent advantage, otherwise the rule would not read as it does. Unless you can show other areas of tennis where specific rules are governed under the advantage/disadvantage (or similar) theory, the FF on Serena should have been called. Note -- I'm not talking about missed calls; I'm speaking to seeing what appears to be a violation by the rules official and passing on the call.
