First of all, it would be libel, not slander, but that's just splitting hairs. What he posted was not even remotely close to libel.
He called him (essentially) a bad businessman, not a crook.
Of course claims made with verifiable facts and/or links are more useful, but if we're going to attack someone every time s/he voices an opinion (and one that is perfectly reasonable based on the information we have), then we might as well shut down the board.
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