The Torah’s dictum that a husband is the authority, is not limited to minhugim. In fact, it has nothing to do with minhugim — as regarding minhugim both the husband and wife are bound to them regardless. The husband doesn’t impose his minhgim – the wife is naturally bound to her husbands family’s minhugim per halacha.
The authority Rav Miller was speaking of is in general. And Rav Miller didn’t make this stuff up, nor is he the only one to say so. See the Shulchan Aruch cited earlier.