Grab the private key?
For the benefit of readers who don't twitt ...
Who exactly can grab this private key, and how? Surely a private key that can be accessed by an unauthorised person is a big no-no, but orthogonal to an idiosyncratic DNS usage?
DNS is designed for performance over security, which is a major reason we don't rely on it for secure transactions and have SSL certs. When you describe a DNS entry as a vulnerability, it looks as if you're suggesting a misplaced reliance on something that's inherently insecure. Or in other words, propping up the edifice by painting over the cracks.