I would say not all that ironic. Book publishers, Reddit, Stackoverflow, etc., tried their best to attract customers while not letting others steal their work. Now Anthropic is doing the same.

Unfortunately (for the publishers, at least) it didn't work to stop Anthropic and Anthropic's attempts to prevent others will not work either; there has been much distillation already.

The problem of letting humans read your work but not bots is just impossible to solve perfectly. The more you restrict bots, the more you end up restricting humans, and those humans will go use a competitor when they become pissed off.