I wouldn't read too much into it. His comments about cryptocurrencies in the past show that he has no stake in crypto and didn't spend much time getting acquainted with the technology. My guess is that he either received the book as a present or is simply catching up with recent developments.
Would agree to this, but it's very well possible that recent mainstream exposure of BTC has made him interested as well. Obviously we shouldn't assume anything based on an picture of him holding a book, but Its possible he would give it a read.