This setup is very poor. The screws that are in the wood should be through bolts from side to side with grade 8 steel, flat washers and self-locking grower nuts. It is VERY DANGEROUS, not when it is without tension, obviously, but when it exerts force.

Assembly requires no more care than having the correct tools. A system with a tourniquet or threaded rod could help you, it is a matter of how your ingenuity helps you. That they charge you 250 for that is a real robbery, but a cosmetic surgery or losing all your teeth or an eye or both because a metal piece jumps at high speed I think it's more expensive.

Anyway, that is an extension spring, so being in the position shown in the photo should not be exerting force, it would be enough to unhook it by pulling a couple of inches to perform the task you want, Wear protection, thick leather gloves and tools that are of quality and do not slip. You should have help, if possible from someone with enough physical strength to keep the necessary tension while you remove or move the hook. BEWARE, better safe than sorry. Greetings from Argentina