> That's not non-determinism, is it?

In the context of discussion, yes, as the only input is considered to be the source code. It is both non-deterministic in compiler output and in program function (two different builds of the same code will produce programs that do different things). Side channel inputs like time are not considered here. If you are trying to start a new thread again and you want to include time as an input in that discussion, then no. However, the same is true of LLMs. They are 100% always deterministic when all inputs are accounted for.

Obviously. Working computers fundamentally cannot operate non-deterministically, although in the real world can appear to when some or all inputs are not accounted for. The discussion is premised on non-determinism meaning "some inputs are ignored".