If whoever sent the telepathic message was able to see what Yeowun was doing and seeing, then it meant that whoever it is was inside the restaurant. Chun Yeowun then heeded the threat from the telepathic message and pretended if he was focusing on the meal. Mun Ku and Hu Bong were talking to each other for any sign of enemy who they weren't sure when they will contact them. Yeowun thought if he should let Mun Ku or Hu Bong know through telepathic message, but changed his mind in case the enemy can see him sending a telepathic message through looking at his neck moving.
'They aren't just any enemies.'
The level of threat was much different from that of cadets from the Academy. As Yeowun stayed silent, another message came to him.
[I'll warn you. Don't try to even find me through your senses. If you try anything stupid, 'he' will die.]
They were threatening Yeowun as if they already knew Yeowun found out that Guard Jang had gone missing.