Yet another legendary investor is calling out Bill Ackman for his controversial bet against Herbalife (HLF). Late last year, Ackman made a public presentation calling the nutritional supplements company a pyramid scheme. He also said he had bet $1 billion against the company.

Leon Cooperman, who runs hedge fund firm Omega Advisors, wasn’t directly knocking the investment. And he said Ackman is “one of the best investing minds around, and his research may be right.” But he also called Ackman “foolish” for making his investment so public. By doing so, Cooperman said Ackman has taken on a public responsibility that he now has to defend. Cooperman said if Ackman were to change his mind without telling the world, he could be in legal trouble.

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“Someone else who followed his advice and shorted the stock could turn around and sue because they were misled,” says Cooperman. A short position makes money when a company’s shares fall. “That’s a real risk.”

Cooperman made the comments at a dinner hosted by Mario Gabelli for Columbia Business School in Omaha that coincided with Berkshire Hathaway’s (BRKA) annual meeting. Ackman has gotten worse criticism in recent months, from Carl Icahn in particular. But what made Cooperman’s tongue-lashing notable was that Ackman was in the audience. Ackman declined to comment.

Challenging Cooperman, someone in the crowd stood up and asked why Ackman’s Herbalife presentation was any different than one Cooperman had made earlier in the evening where he recommended nearly a dozen stocks.

“I spent two minutes on each stock,” said Cooperman. “Ackman spent three hours trashing a company.”

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Gabelli agreed there was a difference between investors who buy stocks and those who bet against them. Gabelli said he would never tell anyone he was short a company. “When I am long a stock and it’s a big position, I have to publicly disclose it,” said Gabelli. “You short guys don’t have to disclose anything.”

Ackman, who turns 47 on May 11th, appeared to take the criticism from his elder statesmen (Cooperman is 69 and Gabelli is 70) in stride. Earlier in the evening, Gabelli gave Ackman a bottle of Jack Daniel’s Black for getting Fortune Brands (FBHS), a company that both Ackman and Gabelli had invested in, to break itself up. Ackman immediately opened the bottle and began filling up the glasses for the people around him, including, full disclosure, this reporter.