You can make sure people who sign up use their company email. If they are found to add wrong information you can block their account.
You can also give companies an opportunity to reply to a post.
You can also give companies an opportunity to reply to a post.
How would you prove that a submission is not truthful? You can check if it's an outlier but that's definitely not foolproof.
I also looks like they recently released a tool concretely to allow for privacy preserving benchmarking[1]. (I haven't looked into the the contents of the repo itself to check whether they are actually using zero knowledge proofs).