...do the work of an evangelist.
Timothy and Titus were evangelists. They were not pastors.
It is not my opinion that Timothy and Titus were evangelists, it is indicated in II Timothy 4:5. If someone tells you to do the work of an evangelist it must be because evangelism is your charge. In Titus 1:5 Paul directs Titus to appoint elders in every city in Crete. Why? Because that is what an evangelist does when he has finished planting a new church.
However the clericalists, who are legion, counter that Paul wrote, "Let no man despise thy youth," I Tim. 4:12. To them this proves that pastors can be young men. Rather, it proves that evangelists can be young men. Evangelists can be and often are young men. Teachers can be and often are young men. But pastors are first of all elders, and elders by definition are not young men.
Timothy and Titus were given authority as evangelists to preach and to teach the whole counsel of God in starting a new church. When finished with their work they were to ordain elders and commit the church to the Lord. There is no pattern found in the New Testament of evangelists appointing elders prior to completion of the evangelists' work; it only occurs when the evangelist's work is finished.
The conceit of Christendom is that 1) since the three epistles are called "pastoral," and 2) Timothy and Titus must be pastors based on Paul's admonition that they let no man despise their youth, therefore 3) pastors may be young men.
That is the logic, and it is the logic of sophistry. Sophistry is reasoning, even or especially good reasoning, based on a false premise.