The intellectual property law that governs ACM articles is copyright law, not patents. I don’t know who controls these (the ACM or the authors) or what rights might have been granted to the public.
The entire point of copyright law is so that people can make their writing public and still be able to control the right to make copies (for example, into your dataset for training an LLM).
The entire point of copyright law is so that people can make their writing public and still be able to control the right to make copies (for example, into your dataset for training an LLM).