The book is basically about how the ruling class should think about structuring policy and messaging to create the outcomes they desire--"choice architecture". Thaler's work describes how public policy "experts" should frame their messaging such that us sheep submit to their will.
Notably, nothing in the book is about how to make public policy to benefit the actual people--the built-in assumption is that our rulers have the unique ability to see the future that is best, and this book simply describes how to achieve that future. Honesty is not a consideration in itself--it is only one factor among many in considering second- and third-order consequences of particular messaging techniques and policy actions.
Our (that is, the peoples') "best interests" don't factor into their thinking one single iota.
If anyone thinks any of this pandemic crap has anything to do with helping people, at least as far as the rulers go, I feel so sorry for them.