They don't need their own LLM. They can just use existing open weights models trained far more modestly.
Maybe finetune them for some specific task, but TBH something like Deepseek/GLM flash, Qwen 3.8, or even Nemotron are going to be plenty good for automation and chores.
...But the thing is, I don't think Debian can dictate an automation setup to contributors, just like they can't dictate what IDE or other software they use to code. It's up to contributors to be conscientious.