Wouldn't supine be an extrovert type? The supine is described as a passive extrovert that craves social contact but waits for others to come to him/her. To me Supine sounds a lot like an ENFP 9.
When they say it's an extrovert, what they mean is that it RESPONDS (or wants interaction) like an extrovert (i.e. the same as the Sanguine). What we normally think of as introversion/extroversion is EXPRESSED behavior, where it is clearly reserved or "passive". (introverted)
Back when I had someone insisting I was an extravert, and that ENP's were "introverted extraverts" (which matches this description of the Supine) I had to consider that, but I determined that my low expressed behavior does match a legitimate
I preference.
So the Supine's "extroversion" in that sense would correspond more to what the Interaction Styles model calls an "informing" preference. Because they like people, they speak in a more informing tone. (Rather than directive, or indifferent). They are higher in that scale than the Phlegmatic, who is really moderate, though both get lumped together in these four-to-five correlations as the closest thing to each other.
Phlegmatics are called "introvert AND extrovert", meaning they are
inbetween on both scales. They can respond to people or tasks, or take them or leave them. They are not really as reserved as the Supine, needing to wait for others to approach them.
ENFP's, as NF's, I expect to be possibly Supine in Control (if not Phlegmatic). In Inclusion, they are clearly Sanguine. (Which is biggest reason why I could never buy myself being one).
9 always sounded purely Phlegmatic to me, though I have considered it being Supine. I couldn't see 6 as Phlegmatic, though. 2 and 4 also seem like they could be part Supine or Phlegmatic. (2 sounds ambiverted, like Phlegmatic Supine / Phlegmatic Sanguine, and 4 sounds like it is Supine Phlegmatic / Melancholy Phlegmatic, and this seems to be matching from what we're seeing here).
The video of the 6 here makes it really sound like a Supine,
Enneagram Types, Nine Enneagram Types - Enneagram Worldwide
and Supines would naturally have the "phobic/counterphobic" tendencies because they are so reserved, but inpressionable by others.