I do like the layer of indirection, but I have to imagine that someday the shareholders are going to ask "why not target ads like Google is doing" and they're not going to have a good answer.
They've also explicitly stated that they will not record any information about interaction with a service.
Based on Apple's general approach to data security, I suspect that there is no "company A got alias address Y" table. In principle all that they need is a table of alias->real. On the other hand maybe it would be useful to have such a table in the case a site gets compromised/starts selling information?
But they have stated explicitly in a public video that they will not record interactions or emails you send, so I'm sure it would be lawsuit city if the reneged on that.
The email relay address could feasibly be just a reference to that state.
You guys trust companies wayyyy too much.