With the Pegasus gone they lost their only escape route which also meant they had no chance but to wait until Luna recovered. The problem with that was that, if she didn't recover fast enough, then they would be forced to move across the city in complete darkness due to the eclipses being triggered all over the city.
Uriel needed to make a hard choice, to move with Luna on her current condition and look for Sam as fast as they could, risking getting ambushed on their way or to lay low and prepare to move in complete darkness.
In the end, they decided to move forward since Medusa was currently unable to see anyway and darkness wouldn't make any difference to her. Uriel, though, wasn't so convinced since he knew that the reason the eclipses activated their ability because they knew they were there.
