There's nothing unusual in that. Plenty of people read in a fandom for short or long periods of time without any intention of consuming the canon - reading doesn't have a context-understanding requirement. If it did children wouldn't be allowed to read things that are difficult for them and they wouldn't get better at it nearly as efficiently, either. I know my childhood would've been a lot more boring.

It's also completely different from writing, which is generally presumed to have a knowing what you're writing about requirement! Sadly enough, or infuriatingly enough as the case may be, in fandom there have always been people out there writing without knowledge of canon.

The new Bond/Q fandom seems to go further even than that, though. Apparently it was measurably active for some time before the movie came out, and so one of the dudes they were slashing was known only from trailers for at least a month! But even for that fandom, this particular author's note is special.