Yes, not very clever of them.
But I guess you can head-canon it so that Emma implanted some subtle suggestions (like keeping her alive) to Callahan when he removed her collar while staying in the cell with her. He thougth he was protected, but we later saw it was not 100% fool-proof.
The X-men are written ridiculously stupid. For example the X-men doesn't have a team assigned to protecting it base. How crazy is it that people are comfortable enough to attack X-men mansion and the X-men have zero response. It is why Utopia era X-men was the most logic group.
Both side of argument Heroes and villains have ridiculous plot stupidity that you are better off not focusing on else or it could ruin your enjoyment. For example why in the world would you put pre upgrade Cypher in the field,better yet why you put anybody in the field who isn't proficient in combat. I am mean the X-men has reach the point where you can put together a team like Wolverine, Rockslide, X-23, M, Colossus a team where there is little chance of any one getting hurt. At this point they should be Search and rescue, Science and Combat teams. Anti telepathy helmets is least of their worries the X-men go out into the field in unstable molecule suits no kevlar, no side arms.
I hate this devil timeline where they left Tabby on Utopia when she was built for the JGS.
I don't blind date I make the direct market vibrate
I know we have to watch the mansion get blown up for millionth time because well why would the X-men protect themselves first. Also I mean why would a school give logical jobs and skills to characters so characters they would have things to do in team and solo books. The X-men is a better group when you think they are teaching nothing to the next(and older) generation rather than giving them specializations to characters who were made as a blank slate. Because why make Cannonball a Mechanic, Moonstar a Medic, Cypher Tech support, Magma a Pilot, etc and let them function as skilled team when they can be doing nothing instead. I agree structure is bad and evil.