Old man Vince's cunning plan

From MC's Perspective:

Soon, I returned to my residence. The first thing I did was take a bath. Then I changed into comfortable clothes before going to bed.

Meanwhile,

Austin was waiting for Zack's return. He didn't know Zack had returned and already gone to sleep.

Shortly afterward,

He got confirmation from his disciple Leah. Then he understood that Zack had returned.

He left the residence and went to Zack Lockwood's place to check in secret. He appeared above his residence.

He then found someone sleeping inside. After confirming that it was Zack, he eased his eyebrows.

"Looks like he was exhausted," Austin said to himself.

He was on the call with Zack earlier, so he knew Zack had faced Black Mark Warriors and convinced them verbally in the end.

If they had attacked, then Zack would have died on the spot.