Esdras naturally didn't forget about those trouble makers, there were reasons why he ignored them.
The first is to lure them into a false sense of security. He didn't have to be genius to figure out what was going on in their minds right now.
The second reason was of course, the problem with the forest. He couldn't lose sight of the big picture because of small pieces.
The third reason was because of a certain owl that hovered in the forest and kept watch over all the apprentices.
While everyone ignored it he used his [Third eye] on it and discovered that it was a familiar. One of the True mages was keeping an eye on them.
However, Esdras wasn't going to call off his plans because of these reasons, he just adjusted how he was going to take care of it.
At night Esdras had some fun with Celine but before falling asleep he found himself thinking about what Reid and the others were about to do.