In these chapters, Clement defines the ultimate authority sent from God to earth that is objective and tangible. He calls the Scriptures the "true utterances of the Holy Spirit." The people who believe the Scriptures did not ostracize the Corinthian church. The righteous Corinthians were cast of by men who are not holy. If you follow Christ and other Christians consistently shun you, then they are not Christians. True Christians are brothers to each other. If they do shun a proclaimed brother, then they keep a line of communication open and live at peace. Sometimes it is necessary to stand for the truth.
So, knowing that the holy people are the ones who support you, "cleave to the holy, for those that cleave to them shall be made holy." That last clause is not actually in Scripture, nor is it Scriptural. To keep your faith alive, yes you do need to cling to your brothers and sisters in Christ's body. I even believe one person can make another holy by being holy in their presence. But only Christ makes people holy. People are only holy when the Spirit lives within. But then again, if the Spirit lives within a person, then that person needs to cling to other people also with the Spirit in them.