That depends on what you think happens at the Lord's supper and what the Church confesses at the Table.URCM,
No, I don't think that is an adequate fence. Again, we confess the gospel in the Reformed confessions. Confessional Lutheran churches confess the gospel. Confessional Baptist congregations confess the gospel.
There is a reason why the Synod of Dort said, "professes the Reformed religion."
I realize that it is painful in our culture to say to Lutherans (who have no trouble excluding us) and to Baptists (who don't or shouldn't recognize our baptism), "Hey, we love you and we may even have a personal opinion that you are a believer, but that isn't a sufficient basis for formal, ecclesiastical communion."
Allowing folk to the table who deny the validity of our baptism (for those of us who only have an infant baptism) who we regard us formally as "crafty sacramentarians," elevates and imposes upon the congregation personal preference in the same way that requiring the congregation to sing uninspired songs imposes on the congregation a personal preference. The one thing to which we've all agreed, in a Reformed congregation, is Word of God as confessed by the Reformed churches. We haven't agreed about the status of Baptist or Lutheran churches necessarily so a consistory isn't free to impose an opinion on the entire congregation just like it's not free to impose an opinion about hymns. We haven't agreed to that.