Honestly, I would normally not bat an eye at the decision to flag this snarky, but I'm astonished how many blatantly wrong comments there are. Maybe it's just Gell-mann amnesia at work...
It wasn't flagged. decremental is shadowbanned, look at their comment history it's all [dead], not [flagged][dead]. If you don't see [flagged] before a [dead] comment or submission, then it was done either actively by a moderator (rare) or as part of automatic moderation.