Just noticed something -- other than Mirror (and Activation, if we include that), all of those types are either the same
Cognitive Style, or the cognitive style of your Dual. By logical extension, could we also include Supervisor and Benefactor?
Come to think of it, when I have to take charge of a group of unruly people, I do adopt an SLE "mask".
Working hypothesis: when a person adopts a behavioural mask or persona, it will be either of a type in his own quadra, or a type that shares the cognitive style of himself or his dual.
Of course, that's just a hypothesis based on the current evidence. There may be evidence which contradicts it.
[On the other hand, maybe we could eliminate Activation after all -- the "Mirror" thing may just be a case of relying on your secondary Ego function. Or maybe when people think they're acting like their Mirror, they're actually acting like their Supervisee? Hmm.]