I suppose this suffices as a technical explanation, but I don't know. Wouldn't he still need to know the creature he's transforming into for the Protean's Alter Shape to satisfy the Escape? I don't know if that is knowledge MitD possesses, since he doesn't seem to know what he is himself, though I guess that's too subjective to judge either way.
I don't have opinions on the Protean either way, though I'd be surprised if MitD revealed himself to be the shifting mass of flesh that is the Hagunemnon, since I've been reading the descriptions of his capabilities (i.e. the stomp, swallowing Redcloak whole) as suggestive of appendages that aren't constantly changing. That's my personal read, though, and I admit it would be kind of amusing for RC to betray Xykon, and MitD having an, "ugh, hold on, one second," moment as he morphs back into having a mouth to satisfy Xykon's command for him.
Unrelated: I looked back at the SRD page for the Hagunemnon and noticed it has "immunities," though the page doesn't articulate what they're actually immune to. Does anyone know what it's immunities actually are? I'm curious!
It's also not great to have voting periods follow one another so closely, especially when the last one was against making any changes. I think it'd be better to wait, especially since the last one was so contentious.