I think you meant that the literature is kosher enough for you. There was no questions of whether Holmes was Frum. He wasn’t even Jewish!
With any literature (even 100% Jewish books) there is always the issue of Bitul Torah. A Frum Man should be focusing his time on Torah and mitzvos, not wasting it on reading books (or posting on YWN.) Except in between, for a few minutes here and there when you need a break.