Pati poked his head out to see the person inside the toilet, completely not expecting anything.
At the very least it's probably a survivor that is alone and scared so he/she decided to hide in the toilet, he was not suspecting anything as he intends to keep moving before the sky turns dark. Even if it were really a scared survivor, he would've killed them regardless.
If there's a survivor then there's a probability that they're a part of the Ivory Posse Gang.
With their group closing into Jericho Paradise Beach to take it down, being spotted by a member of the gang will erase the surprise factor that they can use to their advantage. It's not ideal, and Pati doesn't want to risk it.
But when Pati looks inside the toilet, the person inside widens his eyes in absolute surprise.
