I agree and gave him an answer in 9 minutes from the OP's post.Maybe by todays standards in wrong, but in the past people were far less likely to give a shit.
It is a valid question to ask why the idea was shit canned.
I thought I gave a very accurate, albeit flippant, set of reasons why the idea would be binned. The moment some bright spark came up with the idea, any time after Nuremburg, either the commander or the commander's legal advisor would remind the bright spark that not only would the bright spark get hung, but so would the commander. Anybody carrying out the act and claiming "I was only obeying orders" would join them on the gallows.
All other responses appear to agree with my response. Chemical weapons of any sort are always going to cause all sorts of awkward problems when and wherever used.