You mean the eye thing? That's from Cyrillic, a baby of a script (as scripts go) that's still in wide use today. The o-as-eyes is a decorative flourish, a little visual pun - it's still just an o. An analogous thing would be a medieval Latin parchment of, let's say, the Lord's Prayer and it opened with a bigass P with vines, a gargoyle dancing to a cat shredding on the lute and a tiny caricature of the scribe's dad. If someone found that, we probably won't end up with ʟᴀᴛɪɴ ᴅᴀᴅ ᴊᴏᴋᴇ ᴘ in Unicode.
I think wisty was saying you could make the argument that the glyphs on the Phaistos disk were also used elsewhere, but we just don't have any samples.
Oh, sure, if it's about the Phaistos stuff - it sounds reasonable to have them in Unicode to me but much more importantly, I'm oversimplifying/butchering/misremembering whatever the actual Unicode rules are. You're better off just assuming I'm wrong about their details in important ways.
