Doesn't this mean Sydney can already alter the 'outside' (non-bing.com) world?
Sure, anything can issue http GETs -- doing this not a super power. And sure, Roy Fielding would get mad at you if your web service mutated anything (other than whatever the web service has to physically do in order to respond) in response to a GET. But plenty of APIs do this. And there are plenty of http GET exploits available public database (just do a CVE search) -- which Sydney can read.
So okay fine say Sydney is "just" a 'stochastically parroting a h4xx0rr'. But...who cares if the poisonous GET was actually issued to some actual machine somewhere on the web?
(I can't imagine how any LLM wrapper could build in an 'override rule' like 'no non-bing.com requests when you are sufficiently [simulating an animate being who is] pissed off'. But I'm way not expert in LLMs or GPT or transformers in general.)