Pershing Square Capital Management’s Bill Ackman and distinguished lawyer Martin Lipton (who has spent much of his career defending boards from activists like Ackman) traded thinly veiled barbs at Grant’s fall conference on October 21st, presenting the best and the worst of what activism can accomplish in a pair of talks, according to Grant’s Interest Rate Observer, a copy of which was reviewed by ValueWalk. Lipton calls out rough tactics without naming names Lipton started off the exchange with his speech titled “Activist Interventions and the Destruction of Long-Term Value,” arguing that corporate boards should consider a wider array of constituents when…