Dear Frictional (some advice)

[Romulator]

I am aware - just contributing to your "There are doors you can legitimately lock" statement; not necessarily the OP. Sorry if that did not come out right! D:

Anyway, towards the OP:

Remember, this game isn't necessarily about cheating death by trapping the monster. It's about the horror factor that you're helpless to defend yourself, and while solving such a puzzle could work for your benefit, it does not as the proxy is capable to moving through the ventilation systems. It's not exactly a workaround mechanic to keep you in the horror, but to not allow you to so easily get away with outsmarting the monster. You're hinted at this somewhat constantly post-DUNBAT activation. If you walk under a vent, you can hear it moving around above you.

I will admit, I found this section quite annoying sometimes, I wondered why dropping a fire extinguisher would make no sound and no monster appear, but why fiddling with the elevator mechanism by opening the component's door made no sound but caused the proxy to stick around. I did not know I could trap the proxy, and if I play through again, I'm not going to.