User blog comment:Morganaforever/Episode Review: The Dark Tower/@comment-4879894-20121110213037/@comment-5674726-20121110233638

''A question bothering me. Nobody wonder about how easy it was, after Elyan's death, to take Gwen out the tower. They didn't meet Morgana, and nobody suspected that something got wrong. Perhaps they were to concerned about Elyan. ''

Morgana had a substantial headstart, so for all the knights knew, she might have brought Guinevere to the Dark Tower, stuck her in the room where Elyan found her and enchanted the sword to kill whoever came to save her, and then left before anybody arrived. They could think that Morgana underestimated them, trusting in the traps to take out anybody who showed up. Guinevere probably told them as much.

It's unlikely that they wanted to continue to explore a booby-trapped tower, especially after losing one of their own.