This is grounded in the assertion that a website’s HTML/CSS is a protected computer program that an ad blocker intervenes in the in-memory execution structures (DOM, CSSOM, rendering tree), this constituting unlawful reproduction and modification.

This is ridiculous... the in-memory structures are highly browser dependent, the browser is the one controlling how the DOM is represented in memory.. it would imply that opening the website AT ALL in a different version of the exact specific one they target or with a different set of specific features/settings would also be a violation, since the memory structure would likely be different too.

At that point, they might as well just ask for their website to not be visited at all.