On the other hand, Titus was an uncircumcised Greek Gentile who was accompanying Paul and assisting in his ministry.
"The "false brethren," Ga 2:4 ("certain of the sect of the Pharisees which believed," Ac 15:5), demanded Titus' circumcision. The apostles, however, constrained by the firmness of Paul and Barnabas (Ga 2:5), did not compel or insist on his being circumcised. Thus they virtually sanctioned Paul's course among the Gentiles and admitted his independence as an apostle: the point he desires to set forth to the Galatians." Jamieson-Fausset-Brown Bible Commentary
Paul brought Titus about with him as a living example of the power of the Gospel upon the uncircumcised heathen. Jamieson-Fausset-Brown Bible Commentary