You don't need an arbitrary message to not prove a premine....
Y'all really grasping at straws here.
I'm making light of it all because I don't think there is any issue here.
Discussion
You may be right about the premine. IDK. But I know that writing a one sentence message into the Genesis block to explain the purpose of bitcoin is not "arbitrary" nor is it the same as stuffing jpegs into the chain.
Reconcile it all you want. It is absolutely arbitrary... Don't just say it isn't because it does fit your narrative. Be honest.