Just have a form over HTTPS that store it somewhere in your Vault so that you can move it where appropriate later and add the instructions for power users that

Just have a form over HTTPS that store it somewhere in your Vault so that you can move it where appropriate later and add the instructions for power users that want to use PGP before sending it on the page. It will be convenient and secure for everybody, and users wanting an extra level of security can use PGP.