I'd quibble with the word "know" and replace it with "strongly suspect".
Oh, I understand the argument, and it's a good one, but there are plenty of real-world cases where a system starts off perfectly balanced and ends up lopsided - the concept is called symmetry breaking (which I'm sure you know better than I!)
We cannot a priori rule out some such phenomenon, so we can't say we know for sure that matter and antimatter have different rules.
---
The validation of the Standard Model has been going on all my life, and I don't think anyone expected us to end up in the place we are in now - where the Standard Model has been validated more thoroughly than most scientific models (many writers say more thoroughly than all scientific models, but I believe that the heliocentric model has even more validation), and yet we also know for sure that there's something wrong, because of the fundamental inconsistency between relativity and quantum mechanics.
It's maddening, and it's exciting.
It's likely these new results won't go anywhere - not that I know any details at all, but statistically the majority of experiments amount to nothing, even ones that are initially promising - and that's maddening.
But it also seems likely that putting together anomalous observations like this will eventually lead us past the sticking point we are at now, and that's wildly exciting!
Thanks for another fascinating article.