I find this a rather dangerous precedent. At best, it's an incompatible extension over what would be standard email and it further expands Google's walled garde

I find this a rather dangerous precedent. At best, it's an incompatible extension over what would be standard email and it further expands Google's walled garden, and at worst it sets up a false expectation of security, ending up as little as snake oil and possibly setting up people to dangerous situations. Nothing hints at messages being PGP encrypted (Or being encrypted, period. "Recipient verification" just looks to me like a way to get an acknowledgment of receipt) or even how Google disposes of "expired" messages.