How is it they “could not” have a Mass? My husband was a baptized Baptist and we had a nuptial Mass. I don’t remember it being an issue at all. We even had my husband’s Baptist pastor brother-in-law do the First Reading.
Maybe the regulations have changed. My son and now daughter-in-law were told that since she was not Catholic they could have a ceremony but not a Mass.
Whatever it is it worked out for all of us involved. My daughter-in-law wanted to have a Mass and did what she needed to do to get it.