Pressure
Laeron, Zindi, Matteus, and Ameron still hadn't left. How could they, they were waiting for a proper opportunity.
The truth was that although Laeron's plan was excellent, executing it would be far more difficult. It wasn't as though they could just plop a bunch of novels and movies in front of King Arthur and expect him to read and watch them all.
Whether he even would was one matter, but by the time he did it would probably already be too late. Who cared if Arthur threw a fit after Camelot had already been assimilated by The Empire? By then, they could just send someone to kill him with ease and it wouldn't matter in the slightest.
"… Our best bet is most definitely an illusion specialist. It will be difficult finding one strong enough to cause him to fall, and even more expensive, but it will be worth it. It's the most seamless option we have."
The four of them seemed to all agree with this.