you actually can lower tuning with a narrower port at the expense of port area. With his old port he's also getting over 22 port area per cube lol. Overly wide and long port length is just wasted cubic feet space and with too much port area the sub can perform like it would be in free air, not building up any backpressure.
If he made his port longer, he would not even get that much of a lower tuning because he is losing airspace along with it and less airspace = harder to get lower tuning aka severe diminishing returns after a certain point.