The entire Netherworld Sect has only two Saint Realm experts, so naturally, they can't come out to monitor Trevor Baillie.
The reason Trevor Baillie hasn't left is because of people like Taoi Romero. He's constantly thinking of ways to rescue Taoi Romero and the others, and then leave the Netherworld Sect.
However, he hasn't found the opportunity yet.
Because he discovered that the Deputy Sect Master who initially brought him back to the Netherworld Sect seems capable of guessing his intentions and occasionally takes the initiative to monitor him.
Even when the Deputy Sect Master of the Netherworld Sect isn't watching him, it's still difficult for him to rescue Taoi Romero and the others.
Simply because there's also a 'Half-Step Saint Realm' presence stationed at the place where the prisoners are laboring.
If he gets close, the Half-Step Saint Realm would immediately notice. He can escape alone, but wanting to escape with Taoi Romero and others is somewhat unrealistic.
