It seems you're reading too much into it. It's unworthily, not unworthy and/or non-member. I've met so many people who are not members who are a whole lot more worthy than me. Besides, one time my grandma came to church with us. She's was Catholic. So when she saw the sacrament, she naturally partook of it. There was a prayer, and the passing of the emblems. Nothing out of the ordinary about that with her and I suspect others not of the LDS faith.
Worthiness is a personal thing. I wouldn't tell anyone to not take the sacrament. I figure that job ultimately belongs to the Bishop, who is their Judge in Israel.