What gets me is all this talk of an employee making their terms of employment known (this so-called "ultimatum") being somehow unusual. An employee/employer relationship is ultimately a running series of ultimatums. What's really discouraged is making each one explicit, but of course, that doesn't mean they aren't there, nor that occasional forthright discussions aren't customary. What do these people think a performance review is?

Usually the goal of management is to employ explicit, stop-gap communication to avoid having to get to the explicit question of continued employment, because the company has already made a committment to that employment by hiring the employee in the first place. Obviously, most employees want to continue on, also. So it seems nonsensical to view anything save an explicit declaration of resignation as the same. "I would like to discuss what would cause me to resign," is not a declaration of resignation, and the people reading this situation in good faith understand that.