100% absolutely noise, even if from Real Satoshi. The bitcoin-dev mailing list is for development chatter regarding the Bitcoin consensus protocol and associated technology. However, moderation policy is uh... well, the best way to describe it would be "confused" at the moment. If maaku thought it was on-topic, while Luke-Jr thought it should have been rejected, that's an excellent sign that the policy is insufficiently clear.

I probably have rejected the email and asked 'em to send to bitcoin-discuss instead.

But really the only way to get any hard evidence is a signed message from what everyone believes to be the actual Real Satoshi key... or possibly an early coinbase output, I guess.