he looks nice. A couple points to consider:
1. Generally most snake folks recommend leaving the snake alone to de-stress and acclimate to their new environment at least 2 weeks before handling (changing bedding, feeding, etc. is OK, but wait to handle). Also, people alternatively recommend not handling until the snake has eaten at least 2-3 times consistently for you.

2. I am not sure with STPs, but with all of the other snakes I keep, you need to wait at least 48 hours after eating to handle, otherwise you risk a regurg which can be bad for the snake.

3. You might want to consider replacing the plant hide with another black one (like the one in the pic) that is the same size. This way, he has two options for temperature (I assume you have a hide on the warm and cool ends of the tank) but they are both the same.

Given that you just got him on the 2nd, I'd give him a week or so to settle in before continuing your handling. I am not sure on the feeding schedule for Borneos, but I assume they are once a week.. I'd feed him on whatever day is one week from your last successful feeding attempt, let him digest for a couple days, then try handling again.

Is this your first snake? Just curious as most people don't choose a STP for their first (due to the possible attitude and trickier handling). I hope you have good luck with him!