Like some have already pointed out, it's now very new. I've also encountered it on Bitcointalk weeks ago. I think it's understandable why he'd say that: he probably doesn't know much about what Satoshi wrote on the forum, so it can be a serious risk if someone tries to test his knowledge of, allegedly, himself, and fail. Not to mention that the style of Satoshi from the forum differs a lot from Craig's style (Satoshi wasn't so harsh).
What if we all just stop giving this lunatic what he wants - attention? I don't know if it's right to stop calling him out on his bullshit though, but I feel like crypto enthusiasts are the main thing that still keeps him afloat somehow, in a weird way. Let him destruy himself on his own terms
Well I would agree, but this is bitcointalk where anything vaguely related to bitcoin is posted about numerous times and in numerous configurations and formats. It's pretty slow for news these days so this sort of stuff is going to be talked about. There's also seemingly quite a few people who think he is or may actually be satoshi so that doesn't help either.
I don't think it's right to ignore because silence can be interpreted as a lack of objections. Plus, there are people still sure that Craig is Satoshi as well as many newbies who did not make their minds yet. So it's important not to be silent so that 'team Craig' doesn't win.