Why would someone do this?

So why would someone do that is the question. The answer is to fix the problem. He didn't randomly break open the sewer line he opened the inspection point IP if the system was working as intended there'd be no spill but there's a blockage somewhere and he'll now likely use some device to now remove the blockage.

That door close says "NOPE."

Looks like he knocked the front off the cleanout.

Now he can clean out the clog.

Closing the door on him is insane

Warning: Contains human shit.

How far thought through was this? That dude is not going to be able to get off of that toilet without actually walking in human waste. He should have protective equipment on. At the very least a pair of boots.

Pay your bills!

Coulda put a bucket under it 🤷‍♂️

Workplace sabotage?

Why would you be filming from the splash zone is the better question.