To announce there must be no criticism of the president or that we are to stand with the president, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public.
Either criticism is no good at all (a very defensible position) or else criticism means saying about an author the very things that would have made him jump out of his boots.
It's useful for activists just to be out there to keep you mindful and not get complacent, even if ultimately you think some of their criticism is misguided.
The sceptic will say, 'It may well be true that this system of equations is reasonable from a logical standpoint, but this does not prove that it corresponds to nature.' You are right, dear sceptic. Experience alone can decide on truth.