(Where the double quotes around the ? would be tolerated, which they currently are not)
Is there a reason it can't be made to work?
I'm not sure whether that could be made to work, but wouldn't that defeat the point of using operators, i.e. something rather short, as opposed to functions? (That's also partly one of the arguments against too much escaping: over-complicating what's intended to be a relatively simple notation, as the Hibernate example I mentioned earlier showed: "SELECT ..... \\?\\? ....".)