I'm not sure that quilts, in and of themselves, are supposed to be that warm. Originally, they were layered as the weather called for.
That's what we still do to this day in our house. There are no blankets in this house, only quilts...and we layer them as needed to create the warmth or remove them as necessary as the weather warms up.
You can tell him to add a blanket between the quilt and the top sheet. That would help.