It's not because Google is a user, but rather because he has contributed a significant amount to the part of the Mozilla project that that module covers. That's

It's not because Google is a user, but rather because he has contributed a significant amount to the part of the Mozilla project that that module covers. That's generally how module peers and owners are nominated / chosen. Now the fact that he is an employee working on Chromium may be the reason why he ended up contributing to that part of Mozilla a bunch, but it's not supposed to be "Google gets a peer on the CA module".