The ICPC is a short (5 hours) timed contest with multiple problems, in which contestants are not allowed to use the internet.
The reason most don't get a perfect score isn't because the tasks themselves are unreasonably difficult, but because they're difficult enough that 5 hours isn't a lot of time to solve so many problems. Additionally they often require a decent amount of math / comp-sci knowledge so if you don't know have the knowledge necessary you probably won't be able complete it.
So to get a good score you need lots of math & comp-sci knowledge + you need to be a really quick coder.
Basically the consent is perfect for LLMs because they have a ton of math and comp-sci knowledge, they can spit out code at super human speeds, and the problems themselves are fairly small (they take a human maybe 15 mins to an hour to complete).
Who knows, maybe OP is right and LLMs are smart enough to be super human coders if they just had the right context, but I don't think this example proves their point well at all. These are exactly the types of problems you would expect a supercharged auto-complete would excel at.