Some head coaches in NCAA volleyball intentionally take a hands off approach on the sidelines during matches (like John Cook from Nebraska). For these coaches, they often have a key assistant coach pacing the sidelines giving the players input and information during the match. My observation is that Coach Katie from Penn State is pretty involved. Her style doesn’t really seem much different during her illness than it has been in the past.
FWIW, volleyball isn’t a game where the coach needs to be providing guidance on every point. There is a game plan and the players have been given a scouting report about the other team so they already know what they should be trying to do. Of course coaches are needed to make adjustments and provide feedback on specific situations, but most of their job is done before the match begins.