You can't just cut the power on the unraid server, i assume you're using a UPS in this scenario, which will do a clean powerdown when you cut power. Besides the fact that you are abusing the UPS this way, there is a bigger risk. Normally, in case of a power loss, you not only want to powerdown the unraid server in a clean way ASAP, but after that is done, also shutdown the UPS. If you don't, in case the power returns for like a minute or a few seconds and powers down AGAIN, you will be in the middel of starting up your unraid server again (because your using 'resume on powerloss') and you can't do a nice powerdown since the UPS probably is empty or near empty... this is why you do NOT want to resume on powerloss. Just stay off.
So, do not use the UPS as a handy on/off switch... it's an emergency device, treat it as such.
While I fully agree with what you said regarding a UPS, that is not what was being recommended. Nowhere in the original post was UPS mentioned, but it should have been. The timer use case would be directly on the server power cord, on the OUTPUT of the UPS, not the wall side of the UPS. I agree that a UPS should always be used with a server, and the original suggestion should have made clear which SIDE of the UPS the timer should be controlling. With a properly sized and controlled UPS, resume on powerloss can be applied with minimal risk.