The world is full of people who may want to edit my values ever-so-slightly while I'm not looking, in order to further their own agenda. lso my values may drift, and most drift is harmful from the perspective of my current values. A good recipe for countering this insidious deterioration of values is to consciously pull them back toward their original source, as long as it's something unchanging, like a book.

The argument assumes change is necessarily for the worse. People can aquire new values whilst seeing them as an improvement. If it is possible to meta-evaluate values this way, then you should seek to improve your values any way you can. if it is not possible to meta-evaluate values, then you don't know that your existing values are optimal or any good at all. Keeping them out of sheer conservatism is not rational. Although one could make a half hearted wisdom-of-the-crowds argument.