In my opinion, Yes, the person should be present, if possible, to give him or her an opportunity to hear the accusations and respond, along with their own witnesses when possible. If the person absolutely refuses, then a church is still obligated to fulfill the directions of Matthew 18:17. Matthew says nothing about ignoring this if he fails to show up. The main requirement is that there be witnesses to validate the accusations or problem.

The first goal of church discipline is always reconciliation and restoration (Gal. 6:1f), but if the processes reaches this point, it often evidences a stubbornness or a rebellious heart that is unwilling to deal with the problem. So, for the sake of church purity, which is one of the purposes of church discipline (see 1 Cor. 5:1f), the church needs to proceed, at least eventually having given a time of grace. The meetings need to take place so the whole body can act in accord with verse 17b and 2 Thess. 3:6-14. Without this, there is no power to bring correction or protect the church in the discipline procedures.