If taking off into a 30 knot headwind and a RTO is conducted as per book, then at the call of 60 knots by the PNF, the ground speed would be 30 knots - thus significantly increasing the chances of ingestion since full reverse is still being used at 30 knots ground speed.
If you speak about the ingestion hazard, the relative wind, so indicated speed is the important one, not the ground speed.