Again you think intention means some spiritual super-added component to an act, which it isn't.
Flagrant is a stronger form of obvious but it is neither defined nor quantified.
Moreover, flagrant often refers to a willed act and not an unintended act.
Its not clear to me that the USTA only intends by flagrant the narrow, as opposed to wider, meaning of the term.
The word 'flagrant' invoked by the USTA solves nothing as its meaning is either ambiguous or unquantified.
Moreover, if someone objects to the receiver calling a 'flagrant' ff there is no dispute resolution process.
The rule does not say that the receiver may call foot faults if all else fails, so the word 'flagrant' can always be disputed.
The reality is that the USTA decided to leave it up in the air.