Inflamatory? Because of your suggestion that voicing your displeasure with someone is harassment? Then I agree.
Not even close? No, it's not. The owners/management of the lunch counters had every right to limit their clientele as they saw fit. The demonstrators, though I agree with their goal of racial integration, were trespassing where they had no right to be and were in fact violating the rights of the bigoted store owners.
People writing nasty letters to this mat company at least aren't violating anyone's rights.