I don't see GP claiming CAs should be checking reputability for domain issuance certificates. But the thread originator mentioned subverting CAs! Something to remember about even the most advanced attackers is that they value the continued effectiveness of their tactics, tools and procedures. Even nation-states in possession of CA subversion abilities won't burn their malicious CA on someone if they can conduct the attack with a legitimately-issued certificate, and they won't bother with a legitimately-issued cert if they can conduct the attack without even involving a CA.