If I went to my mother and said ' Husband does not want you to come to his mother's funeral ' she would say 'why?' and either I would end up spelling it out in actual words or I would attempt to obfusc and she would know that the answer was 'because he doesn't like you.'
My mother is polite and not given to blood feuds but her feelings would be hurt. Rightly so. She would not have a show down with my husband but she would probably politely excuse herself from our family occasions after that. There might be a slight chill between us. My children would see less of her. I would have to go out of my way to see her without my spouse being there. I could not talk freely to her about my family life after that.
My siblings are not so polite. I guarantee we would have arguments about this. They would argue with me and they might argue with him. They might have words with my husband and they might be unforgivable words. I suspect my spouse would be explicitly excluded from all family events after this hypothetical event, certainly if my mother was invited, and my family would not attend ours. So every time I wanted to see a member of my family, attend a birthday or a wedding or a Christmas dinner or, yes, a funeral, I would have to say to my husband 'You are not invited because they don't like you. And also my mother is coming and she doesn't like you either, now.'
And then I'm visiting people who think my husband is so awful that they won't have him in the house. Do I take my children into that environment or do they never see Uncles, Aunts and cousins again? How do we explain why their cousins and Nana have stopped coming to birthday parties at our house? Is my husband ok with me still seeing them alone or do we argue about that, too?
Suddenly, I'm guessing, the subject is coming up on a regular basis, every time a family event approaches we go over the time he said he didn't like my mum and she's not a member of his family and he didn't want her at a funeral, and then as a result I had to go and hurt her feelings and I was put in a difficult situation I didn't want to be in. By him.
Maybe I 'm thinking, 'where does that leave me? Am I member of your family?' Maybe every time the problem comes up, I think 'yeah, my siblings are right. You are an arsehole and you don't give a shit about my feelings. You gaslighted me and said I was sulking. Maybe my siblings, who I like and trust, actually have a point about you.' And then where do we go?
Anyway, this is all hypothetical obviously. All families are different, but that's roughly how it would pan out in my family.