Security cables are for cameras and sensors so you should already be warned before they cut the cable. Also on the shop end only the gas line enters the building through the outside wall so to cut the cables they have to find the source. and if they are willing to do that I doubt you are going to stop them. I tried the wifi route between the shop and house and found it to be a PIA.
As usual, I wasn't very clear. I was talking about the alarm monitoring service not the alarm function. Phone lines, internet cables, and other wiring is usually above ground where it enters the house. Easy peasy to cut. We recently added a cellular monitoring connection from inside the house.
Yes, I am leery of WiFi based alarm systems too.