We disagree on this one, Justanother. Hubbard's "claim to fame" was not as a writer on diverse topics (though he did write other sorts of fiction), but specifically as an author of stories and novellas in the science fiction pulps, especially Campbell's Astounding, where, as you say, he first published Dianetics material.  Just as A.E Van Vogt (another Dianetics supporter) or Robert Heinlein would properly be billed as science fiction writers, so should Hubbard.  It is clearly the one thing for which he was best known in 1950, and it remains an important part of his career.  There's no shame in it.