Nope. Maliciousness is only required to be proven if the person is a public figure (see Times v Sullivan). Besides, as I mentioned, it is not so much that the person could win, but that he could sue with the attendant lawyers fees. You can argue the esoteric points forever, but it in the final analysis, you have a couple cents tied up in typing and printing "allegedly" vs $10,000 and probably much more in potential attorney's fees to win a case. No brainer in the real world.