The response was fine, in the same tone as the original request even if the first one was offensive by accident. A kind, functioning human would be puzzled at the slightly blunt response and re-evaluate the whole conversation.

They would not go to a private channel, knowing that they would get blasted for such a response in a public forum, and get even more offensive. Plus, any non-native that has an advanced enough understanding of English to use the phrase 'thinly veiled extortion' can also control the tone of their requests. No need to defend IBM here.