I agree, the referee should have waited until the player leaves the field, but just being the devil's advocate for a moment, how is this any different to play carrying on while a player upfield is receiving treatment, and despite being technically offside, he suddenly gets to his feet and rejoins play and assists a try being scored, or scores one himself. We have seen this in top level rugby, and it was "play on"
PhilE... a Zambuck is someone who treats players on a sports field, mostly in Aussie and NZ. The term derives from "Zam-Buck" cream (a medical pain relief cream similar to "Deep Heat") which was made by Zam-Buk Company of Leeds.