Simple Motor Tics - Blinking, Jerking, Twitching
Sometimes doing something is good. Sometimes doing nothing is better. This is one of those times. The primary recommendation for creating a healthy and safe environment for people displaying motor tics is to ignore the tics.
A player displaying such motor tics is not able to control them. ANY course of action that directly relates to affecting the likelihood of a tic, whether it be suggestions toward suppression, or attempting to remind the person of the tic when it occurs, is very likely to only encourage the tic. Separately discussion can occur with the group to hopefully impart an understanding that the tics are likely to happen, out of anyone's control, and that they will generally not be impacted by them. By being aware that the tic will occur, and that it is not in the control of the player, they become easier to ignore, and hopefully the person experiencing the tic will not be affected by external pressures that are associated with the condition.
In any case, ensure that there is a space available separate from the group, that a person who displays motor tics may if they want to, move to in order to reduce anxiety and return to gameplay.