What's dumb about that attack? It has a fair number of LS, to ensure that the transports aren't sunk unnecessarily, and enough land troops to clear whatever a regular 1k city can produce. Forgetting a revolt is something that even the best players are guilty of on occasion. It seems that the only thing about it that may be slightly naive was not to precede it with a spy (which he likely did), or to send attacks before the CS (which he may well have done, you don't say).
Nothing dumb about that attack itself, and it certainly isn't "the dumbest attack ever". If you consider instead his attempt to conquer a 1k city to be dumb, then I'd be forced to ask why that is dumb, yet colonizing a city is not. Clearly you have enemies, so while you waste time and troops to defend a newly colonized city and then post on the forum about how "dumb" other players are, you could have been conquering larger cities..