Sure. The WSR equipment specs say:
The cue tip may not be of a material that can scratch or damage the addressed ball. The cue tip on any stick must be composed of a piece of specially processed leather or other fibrous or pliable material that extends the natural line of the shaft end of the cue and contacts the cue ball when the shot is executed..
Of course you don't have to accept anything from the WSR and can modify them any way you please since you are the TD running a local tournament, but the specs do not allow the kind of phenolic tips I've seen.
If you're going to depart from the official rules, I think it's a good idea to write down all of your personal exceptions and make that list available to the players. On the other hand, I've met several TDs who would rather not have a clear, written set of rules so they can adjust the rules against the players they have problems with. Yes, I've actually had TDs tell me that.