“Presumably he thought he was following the tzivui, after filtering it through what he thought Hashem wanted”
When Chizkiyahu didn’t do peru urevu I would presume that he didn’t think that H’ wanted him to do peru urevu but he didn’t do it anyway beacause he didn’t want to have bad kids. Presumably he thought that since he would have bad kids, H’ would want him to not have kids. Yet Yeshayahu told him ???? ???? ?????? ??? ?? ??? ?????? ????? ?? ????? ??? ????? ???? ????? ???? ??? ?????