Well, now we have an official interpretation published by the NCAA (Randy Bruns). It seems to counter his previous email:
Physically Assisting a Runner – Rule 8-5-f
Interpretation:
A runner is out when:
f. A coach or any other member of the offensive team other than another runner, by touching or holding a runner, physically assists the runner in returning to or leaving a base.
Note: The touching of a runner alone does not constitute physically assisting; however, when the touching improves the runner’s chances of accomplishing their goal (retreating or advancing), it should be interpreted as physically assisting. A runner is allowed to assist another runner physically; however, all other members of the offensive team (e.g., base coaches, on-deck batter, a runner who had just scored or has been put out, a batter, etc.) are not allowed to assist. When a play is being made on the assisted runner, the umpire should call “Time” and enforce the penalty; the runner is out, and all runners return to the bases occupied at the time of the interference (assistance). If no play is being made on the assisted runner, the umpire shall signal that the runner is out and allow the ball to remain alive.
Rationale:
The physical assistance of a runner by another offensive team member other than a base coach or another runner most often happens in the vicinity of home plate where a team member is often there to “coach” the runner trying to score when and where to slide to avoid a tag. It is unfair to allow any physical assistance by another team member to impact if and when the runner touches the base prior to a tag, appeal, or video review. Although not specifically covered in the NCAA Baseball Rules, this ruling is based on common sense and fair play. This enforcement principle permits the defensive team to make plays on other runners, if possible. If the ball were to instantly become dead at the time of interference (assistance), the offensive team could always control the status of the ball by grabbing a nearby player.