I disagree with the parent's wording and agree that the whole "people are free to say what they want" thing is generally not a compelling point in internet arguments, but there is a distinction you are omitting. People aren't just disagreeing with DHH's politics, they're implying that his project shouldn't be financed because of his politics. In that light, your counter-point isn't as applicable, since it's not symmetrical to what the parent is criticizing (regardless of whether you believe his politics are worthy of black-listing his work).