A very rational choice by Anthropic.

The cost of blocking videogame reverse engineering is trivial. They added three lines to the system prompt to exclude it and probably made a small update to their backend training classifiers. They give up the videogame reverse engineering market, which is a tiny future revenue stream and not worth much financially. In exchange they avoid hundreds of millions, maybe billions, in future copyright lawsuits.

Providing this service has negative expected value. It's better to cede the market to someone else.