Another interesting scenario would be, what about those members who do not hold the Priesthood or even non-members who may pretend to be members and go around other wards and maybe give blessings, etc. Are those ordinances valid? I know it may sound strange but it COULD happen.
That sounds like it would be just as good as if an unworthy man performed the ordinance. Both are impostors, pretending to hold authority that they don't have.
One thing that happened on my mission, which isn't quite on the same subject, but one of the inactive members decided he wanted to be baptized into the church again to have the spiritual experience again (which actually used to be done in the pioneer days) but he tricked the missionaries into teaching him the lessons as if he were a new investigator & was rebaptized into the church! The funny thing was, some of the members knew who he was & failed to let the elders know about it. They were teased a long time for that one.
I get the feeling there will be a lot of priesthood holders and fraudsters being held accountable for the way ordinances of the Lord were handled.