Not sure which thread you're referring to, but yeah, it is a legit question. I genuinely wondered what made the OP state that it's proven that mullvad doesn't collect logs. While I don't think it's possible at all to prove that some software is running on a remote server, or that this software doesn't collect logs, some people try to find a way to do that, for example Signal claimed that one can verify code running on their servers by code attestation feature embedded in their Intel SGX enclaves, see https://signal.org/blog/private-contact-discovery/