As a CFI if I told a student he met the PTS 100%, but since he couldn't recover a 3 rotation spin on heading I won't sign him off for his ride, Id fully expect to be taken to court, loose and have my crap put on blast.
The difference is that your student has already paid for, and contracted, services from you. Tom's client has incurred no damages. You would have to compare it with you telling them up front before any training that they will have to perform a three turn spin to a heading for you to sign them off, and letting them decide whether to continue with you or not, and that would be fine.
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