1) The formal exit interview with HR. The HR person was apparently called to do it on her day off (no idea why they didn't just have someone else do it), and made sure I knew it, complained that "we just spent a lot of money on those classes you took and you were on track for Leadership training." Seriously? People leave: it's a cost of doing business!
2) The VP of Engineering called me into his office to say goodbye and ask a few questions. Specifically, he wanted to know if the company's diversity programs were accomplishing anything useful (I'm black) or if they were just fooling themselves. In his words "you already have another job, so I'm sure I can trust you to be completely honest." I took him seriously and tried to give complete, honest answers to. Truth be told, I loved working there. I just wanted to move away from that part of the country and had a great opportunity.
HR's attitude pissed me off so much that if I didn't already like the place I would probably have badmouthed them to anyone who asked.
The HR person sounds like an HR person.
But if you are leaving a company, that's even less of a reason for the person you're critiquing to listen to what you are saying (b/c they can just write it off as someone who has sour grapes or was leaving anyway), and even more of an opportunity to just create unnecessary animosity. And that professionalism that becomes a necessity when the person is still a coworker can disappear completely.
Some people are just insecure and always get offended by constructive criticism, some people have poor communication skills and think they are "just being honest and constructive" while actually being very offensive (we probably all know a few coworkers like this) and sometimes the person doing the exit interview has just had the worst day of their lives. Bland platitudes in the exit interview will almost never hurt but candid feedback can definitely go sideways very quick. Game theory says it's better to play it safe.
I thought about wording it differently (e.g., a person will behave professionally until ...) to help illustrate that but the way I chose to word it also helps to illustrate the perceptions of the other individual: it seemed very much that they were professional until their behavior changed.
Or to rephrase, one who is professional until an actual test of their professionalism.
It seems to me that the author is suggesting a third type of person: one who is professional until they're criticized.