GPT and LLMs don't run code, even when you tell them to run something. They hallucinate an answer they think would be the result of running the code. Presumably these plugins will allow limited and controlled interaction with partner services.
The link talks about tools that 'lie' - ie. a calculator which deliberately tries to trick GPT-4 into giving the wrong answer. It turns out that GPT-4 only trusts the tools to a certain extent - if the answer the tool gives is too unbelievable, then GPT-4 will either re-run the tool or give a hallucinated answer instead.
Again, GPT is not running a tool or arbitrary python code. It's not applying trust to a tool response. It has no reasoning or even a concept of what a tool is--you're projecting that on it. It is only generating text from an input stream of text.