That you can't "become Schwartz" by using LLMs is an unproven assumption. Actually, it's a contradiction in the logic of the essay: if Bob managed to produce a valid output by using an LLM at all, then it means that he must have acquired precisely that supervision ability that the essay claims to be necessary.
Btw, note that in the thought experiment Bob isn't just delegating all the work to the LLM. He makes it summarise articles, extract important knowledge and clarify concepts. This is part of a process of learning, not being a passive consumer.