I was sure he would wake up next morning and find the car missing. I think he was really lucky that this wasn’t the case and the thieves waited(?) for the next night.
When they cut the wire in the pillar, they didn't disable SOS, they disabled the triggering mechanism. The idea being that they would return and break the window again only SOS wouldn't be triggered because that wire was cut.
The next night, there would be no SOS notification when they broke the window again. Or maybe they'd only have to tear away a plastic bag, if the owner hadn't gotten the window replaced.
Or maybe they were hoping to find a valet key in the car, making their job even easier, either that night, or the next night.