I agree with DD, provided the CAT I hold position is at the runway end and not at an intermediate take-off position and the conditional line-up clearance is following another departure from the same point, except if both are departing from the same intermediate position. If an intermediate departure crosses the Cat I hold before a full length departure has passed then this I believe to be an incursion.
In addition to protecting the runway cleared and graded area, for precision approach runways CAT I holds are to protect interference to radio-aids, penetration of the Obstacle Free Zone and penetration of the OCA/H.