User blog comment:Skeith9/Heroic Spirits Speculation/@comment-24982278-20140525073101/@comment-5739199-20140525151929

Who said F/sf is non canon? Just because the writer wasn't Nasu? Then Zero isn't either.

As for why the choice of heroes was crappy, it's explained in the story; the False Grail is gay and can't summon proper heroes.