What if instead of showing people's CPU scores, you instead show a warning flag if they're likely to have too low a CPU for the map in question, similar to how you get a ping warning if someone's ping goes over 500?
It'd be impossible to get a perfect measure, but I'd have thought you could still have a reasonable approximation by considering the map size, and the number of players available on the map, coming up with an approximate CPU score that you'd want to play that map late game without significant slowdown, and then showing a player's CPU score only if they exceed that level.
So for example a 3v3 on a 10x10 map might show a warning if they're about 400 CPU, while a 4v4 on a 20x20 map might show a warning around >200 CPU (testing could be done to come up with better thresholds - I just picked these numbers out of thin air).
This way the person with the bad CPU knows by staying in the game lobby they're at risk of being kicked, while they also dont have to worry about being kicked based on their CPU if they've got a good enough CPU for the map and the host just likes going over the top with CPU scores.
An alternative would be making it a rule that you can't kick someone due to CPU/Country/Ranking/Grey status if you host an "All welcome" game (and reporting and punishing people who break the rule) but my understanding is there's already a large backlog of moderation reports so that's probably a non-starter as an option.