Come on, that was barely a rock!
It wouldn't and I don't. That's not my point.
The point is, the shapeshifting itself might be the main selling point of the Protean, but it is also its main weakness. See, the Monster never ever once exhibits any clear sign of shifting its shape, which is odd, given how (as you have just cited), it changing its features is a trivial non-action, whereas maintaining them has an actual action cost. So… What do we even have here?If it consciously changes into a single creature, sure, but a)I see no reason why we should assume MitD would do that here, and b)We have loads of evidence the MITD doesn't even know what he is or how he does the things he does, which makes it even less likely he would purposely shift into a smaller/weaker creature-- because he doesn't know how his powers work or how to control them.
It reads to me like "MitD is not a Protean because he didn't change size/shape in the way I assumed he would, even though he doesn't even know what he is or that he can do that."
a. The Monster has no control over its shapeshifting whatsoever, because he doesn't understand it. In this case, how he always has two eyes and an appendage at a fixed position, the former having a fixed appearance, as well as always having a mouth-equivalent orifice seemingly at a fixed position when he appears to insert things into it is mighty odd.
OR
b. The Monster can consciously control its shape. An assumption readily contradicted by his own admissions of no understanding.
OR
c. It's vibes-based and instinctive, with features manifesting to cater for his needs without him understanding how the process works. In which case it is odd that he can apparently partial-transform into an Umbral Blot to use an obscure ability he has trouble even naming properly, but when he simply tries to hit lightly, he doesn't even get smaller, although he could trivially achieve that. (I presented the math: it doesn't take weird epic abilities for a full Protean to reduce the damage output of a single hit to a measly 1+11 points.)