There is nothing wrong for someone to change their hanhagos when they marry into certain families, Rabbonim have done it all the time; even my own Rav. And no one has questioned Rav Gonish’s integrity.
But I know Rav Gornish going back over forty years and he has certain chumras which is incorporated into his l’chadchila hashgacha, and that’s why people of like minds use him.