While I agree with the general sentiment of your post, I find quote does not actually work out in practice.
I have been in many situations (ie around family, coworkers, etc) where the group has a strong opinion about something and I feel the opposite. I would usually not chime in and let the conversation move on, but when people ask your opinion, there is a decision. As far as I can see, the options are basically:
1) Lie: not authentic or direct honesty 2) Avoid/Deflect: maintain authenticity, not direct honesty 3) Fein disinterest: lacking authenticity, not direct honesty 4) Express your dissent: authentic, direct honesty
The only options for maintaining authenticity are to be directly honest, or to not answer, and there is a limit to the extent you can avoid answering direct questions and still maintain freedom and conserve your energy and focus.
So while I agree that you don't have to be brutally honest to be authentic, I would say they are far from orthogonal. Sometimes choices have to be made, especially around people who have a tendency to pry or ask your opinion a lot.