It was just too ugly. Even for a temporary server. Especially when you consider all those wires flapping around would impede airflow.
Only took about half an hour of work to rewire it, although waiting for cable tie anchor pads to set (the adhesive wants 24 hours, ideally; and this batch I’ve had pull off in many situations, to the point where if it happens again I’m throwing the rest out) slowed down the elapsed time.
It also made getting the side panel back on easier (this case has a shroud connecting the CPU cooling fan directly to the outside, on the removable side of the case) since the wires were held back. That’s also why the sloppy wiring would work, though—those wires that look like they’d get into the CPU cooler wouldn’t really, once the side panel was on properly.
Cooling is working excellently (the external fan in front of the expansion bay probably helps; that’s held on with cable ties and tape too).