I’ve heard that this isn’t possible - is it a rule, or a practical thing?
It’s mainly just a timing thing. For a rower wanting to make the NZ U23 team, you’re over in the states for too long during the year. To make a crew go fast you need time together in the boat and the states university dates clashes with the NZ rowing U23 dates.
If you want to row in the states its an awesome opportunity but you’ll struggle to come back into the NZ system after being away for about 4 years.