He doesnt understand that feedback system for DHT doesnt work like test. The only feedback system there is, is for test. From your test pool, DHT and estrogen will be synthesized depending on the amount of aromatase and 5a-reductase present in your blood (these 2 enzymes arent really regulated like the test system although theycan be inhbited through aromatase inhibitors like exemestane or 5a-reductase inhibitors like finasteride).
All supressive hormones will supress test directly and from that supression, indirectly supress estrogen and DHT, but only because their precursor, TESTOSTERONE is being supressed.