IMO contestants aren't allowed to bring in paper tables, much less a whole theorem prover. They're given two 4.5 hour sessions (9 hours total) to solve all the problems with nothing but pencils, rulers, and compasses [0].
This model, meanwhile, was wired up to a theorem proover and took three solid days to solve the problems. The article is extremely light on details, but I'm assuming that most of that time was guess-and-check: feed the theorem prover a possible answer, get feedback, adjust accordingly.
If the IMO contestants were given a theorem prover and three days (even counting breaks for sleeping and eating!), how would AlphaProof have ranked?
Don't get me wrong, this is a fun project and an exciting result, but their comparison to silver medalists at the IMO is just feeding into the excessive hype around AI, not accurately representing its current state relative to humanity.
[0] 5.1 and 5.4 in the regulations: https://www.imo-official.org/documents/RegulationsIMO.pdf