alt Hacker News> Training an LLM inherently requires making a copy of the work.
But that's not relevant here. Because the copyleft license does not prohibit that (and it's not even clear that any license can prohibit it, as courts may confirm it's fair use, as most people are currently assuming). That's why I noted under (1) that it's not applicable here.
It's absolutely prohibited to copy and redistribute for commercial purposes materials that you're unlicensed to do so with. This isn't an issue when it comes to the copy-left scenario (though it may potentially enforce transitive licensing requirements on the copier that LLM runners don't want to follow) but it is a huge issue that has come up with LLM training.
LLM training involves ingesting works (in a potentially transformative process) and partially reproduce them - that's a generally restricted action when it comes to licensing.