The man at Cornith was committing blatant sin within a local church, which of course needed to be dealt with in a proper manner. It is the right of a local church to discipline, and if possible, restore the member to the fellowship of the church.
With that said, I have to wonder if this man was ever saved at all, to commit such a sin. It is possible for a Christian to commit a one or few time sexual sin and have Holy Spirit conviction, ask for forgiveness, and return to fellowship with the Lord. However, this passage implies this was an ongoing sin, with no remorse. If a person is truly saved, in a relationship with Jesus, then church discipline, should not be necessary. The Holy Spirit should have taken care of the problem long ago. By the time the situation is so obvious, that it is disrupting the church, it seems to me there is no Holy Spirit to convict, therefore this person is most likely not saved. Not being saved, he needed to be excluded from the local church until an act of regeneration occurred.
So, with that said, what if the church had not have noticed it? The Lord's Supper would have been offered based on his membership in the local church, and it is obvious he would have taken it, since lost people don't tend to self-examine themselves.
Now, today, in 21st century America, look at our standards of church membership compared to then. The standards had to be much much higher then. They were higher 50-100 years ago if you all read your church minutes. Look at our church rolls. We for instance, at one time had near 500 on our rolls as a reminder of what attendence was like in the 50's and 60's. The problem is that 100 is now a good healthy number for Sunday morning and more often than not is in the 60 range. We have gotten our rolls down, but this is my point. If we are running 30-50% attendance at best, less on Sunday night, even less on Wednesday night, how many people on our church rolls have a rock solid, forever relationship with Jesus Christ? This goes for most churches in America, Baptist or otherwise. Church membership has been diluted so many times over it tastes like someone forgot the coffee grounds. And with churches allowing membership by a yea vote and little else, I have to wonder if a church membership would recognize the need for church discipline if it smacked them in the head. Look what is normal behavior today and what was acceptable 50 years ago. Gay priests, same-sex marriages and "alternate life-styles" condoned. The list goes on and on. So we certainly dont see not supporting your local church as a need for discipline. It seems to me most churches are totally in the dark in this area.
Even if I believed in closed communion, with that standard present today even in our most conservative churches, there is no way I can see using church membership as a standard for the Lord's Supper.