Interviewed about it in Time in 1968, at the height of its use in Vietnam, he not only had no regrets, but had no particular worries if the substance continued to be produced by Dow Chemical and consumed by the state military machine in the killing of Vietnamese people. (I almost wrote "civilians" rather than "people" there, but the implication of making that distinction is barbarous). The guy's name, and he should be named, was Louis Fieser. I suppose you're expecting me to say that he was a good man, and the system misused his science but, take it from me, he was a real sack of shit. No worse than many others of his class, of course: hardly any of those in the US intellectual class opposed the use of the substance during the Vietnam War, in the same way that hardly any of the leading intellectuals in the US oppose war crimes in Iraq today.
Most of them are outspoken 'defenders' of the Enlightenment.