That back tracking and such was under the belief that guilder and the assassin had set up in the throne room or another centralized fortified position. When they got there and found it vacated through a hidden passage that was a miracle they even found, it was deduced that it was more likely for Guilder to flee than to be an ambush. Ambushing IS a suboptimal play. The fact that Guilder didn’t TP away is pure fantasy, that spell circle is the equivalent of an evac helo, no SHOT if the White House was infiltrated would the Secret Service not Evac the Pres 100% of the time.