Immorality is subjective. McKinsey is hired to (maximize|minimize) some objective. The fact someone didn’t want to work on the Purdue Pharma opioid marketing project when McKinsey employs a fungible pool of thousands of consultants means nothing.
The Purdue thing was really bad. That’s acknowledged. Nobody is happy about it. Plenty of work has been done pro bono to combat the opioid crisis even prior to the realization of what had happened. I have worked at other places and I legit feel comfortable saying that relative to most American businesses, the firm is not an evil purely profit maximizing machine. Most people’s day to day is benign and well intended and you can just straight up talk to people about it because people are interested in such things.
tldr: while I fully recognize bad things have happened I would say that on average McKinsey is more morally self conscious than your average us company. Take it as you will