Yes, it would adversely impact their profile. The question of course always comes up as to whether having the AU account is a positive thing when high utilization becomes a factor. At that point the AU has to attempt to weigh the benefit of the AoOA increase verses the adverse utilization impact.
If you have relatively high overall credit limits yourself, perhaps the high utilization AU account wouldn't cause your aggregate utilization to cross a threshold, so the impact would be limited to the scoring ding associated with highest individual card balance.
