Republicans in the audience demonstrated their total lack of patriotism and general lack of class by roundly booing the General.
The crowd was siding with the vast majority of the troops. If Colin Powell and hundreds of thousands (if not millions) of officers and senior enlisted men believe that Colonel Kerr is full of it and pushing a dangerous policy, why is it unpatriotic to boo him? They didn't boo his service, they booed his support of a dangerous policy.
Besides, even if the crowd were unpatriotic and classless as you claim, they would merely be emulating your hero, Bill Clinton, who "loathed the military" and certainly is no paragon of class, having used the Oval Office sink as a sperm donation depository.