You are correct! The other person is wrong. Transaction volume has almost zero relationship with mining energy usage (there are some very subtle connections, but those nuances are hardly worth getting into for this discussion).
This is a stupid comparison. The number of transactions can be increased by a factor of a 1000 easily while holding the amount of energy expended constant.
Co-author writing here. Although we think Bitcoin has (probably) a bright future, the book is really just about explaining how it works (the protocol and the cryptography behind it).