He has a point, but he is forgetting something very important. If you do not comply with the laws of a country they hold the right to restrict your content, or even forbid your sales inside of their country until you come into compliance with their laws. While I am not sure if the new laws means any more than a few extra hoops to jump through, I also don't see why you would not want to do a little extra work for the potential to sell there. I mean you research how to market, why would you not want to know how to do that best, everywhere you might sell books?
That said I don't think this is as big a deal as everyone thinks.
Here is what EL said on another thread, and I agree with him,
Not needed. Again, sending out an email stating that is tantamount to admitting that you didn't have consent, to begin with, so if you have a mailing list, you should leave that alone. That's not just me speaking. That's a lawyer, a link to which I've already put up in another thread on this.
The best thing to do is just simply send out an email explaining the GDPR and help people on your list by giving a link so that they can change their preferences. Make it easy for them. Other than that, keep going. Don't give in to the massive fear-mongering that is going on about this and walking on eggshells. That's not doing anyone any good. Make the small changes then go and do what you're supposed to be doing: write.