You see it's not about what we say, it's about what other say, and if 10  huge corps analyse the web and spit out billions of triples saying that anything 200 OK'd is a document, then at the end when we consider the RDF graph of triples, all we're going to see is one statement saying something is a "nonInformationResource" and a hundred others saying it's a document and describing what it's about together with it's format and so on.

I honestly can't see how anything could reason over a graph that looked like that.

However, I'm also very aware that this all may be moot any ways, because many crawlers and HTTP agents just treat HTTP like a big black box, they don't know there ever was a 303 and don't know what the end URI is (even major browser vendors like chrome do this, setting the base wrong and everything) - so even the current 303 pattern doesn't keep different things with different names for /slash URIs in all cases.

Best,