i hadn't heard that. but even if true, increasing your ai will still help. say you have a total estrogen of 30. 10 e from testes and 20 e from the rest. well even if your ai doesn't affect the 10 e, it will lower the 20 e and lower your total estrogen.
ai's only work on estrogen that comes from the aromatase enzyme. there are other kinds of estrogen some of which come from the environment. ai won't effect these but still the primary reason our estrogen gets out of control is due to the test we take, and an ai will certainly lower this conversion and thus total estrogen.
practically it shouldn't matter as bloodwork and symptoms will determine whether to increase or decrease ai, but op should be ready for it to be higher than if he didn't use hcg.