No this is not true. For two reasons.
1. We call these things LLMs and we train it with language but we can also train it with images.
2. We also know LLMs develop a sort of understanding that goes beyond language EVEN when the medium used for training is exclusively language.
The naming of LLMs is throwing you off. You can call it a Large Language Model but this does not mean that everything about LLMs are exclusively tied only to language.
Additionally we don't even know if the LLM is even remotely similar to the way human brains process language.
No such conclusion can be drawn from this experiment.