Every service gets to set their own standards. As buyers, we get to decide if we agree with the service and adjust the price we are willing to pay for the coin, not the slab.
Just because he CAN grade that well doesn't mean that he WILL grade to that level. Especially if it means he can sell undergraded, or problem coins, as higher straight graded. Both of which he was known for.
Can you finish the list?: https://davidhall.com/pages/about-us A conflict of interests in the Numismatic "industry"? Has anyone seen prominent TPG "Principals" become involved in selling their product? NO! LOL I don't know! We might ask eBay, or the "courts", again?. JMHO