No, it means that the reality of catching cheaters in chess is fundamentally heuristic if you don't manage to catch them red-handed.

This accusation hits many of the heuristic high notes.

That doesn't mean he definitively cheated. But to me, with ~15 years of chess under my belt, it does make this accusation credible.

Niemann have admitted cheating before when playing online, so Carlsen is just not making this up about any random player. There is a history of cheating.

Also Carlsen didn't accuse other players of cheating the other times he's lost

The sample size for that is absurdly small. (Carlsen only takes single classical losses seriously, since rapid/blitz is too random.)

There is no smoking gun, but there is a lot of smoke. The ease with which Niemann pulled out of the hand a couple of brilliant moves, without spending too much time thinking about it, on an unusual line, is highly suspicious.