They're saying Graphene without MTE is less secure, which isn't something they want.
Well they're inevitably backing into a dead-end. MTE is obviously off the table now which means eventually they'll have no hardware fitting to their super-exacting demands. Motorola might come through, or not.
I hate being a conspiracy theorist but honestly sometimes the way Graphene clings to Pixels feels like a Google scheme to boost their pathetic Pixel market share.