I've searched the web for any tests for the Osmo mobile's durability but found nothing.

I'm wanting to take it on a snowboarding trip, and want to know what will happen if the camera guy takes a fall while shooting.

You can always just rent one from LensRentals instead pretty cheap with insurance... But seriously, it is pretty well made. If if falls on ice or a rock, both the smartphone and the osmo could get damaged. Filming and skiing isn't that easy either depending on conditions and speed, so the camera guy could also get damaged. I've done it and I do my best to fall on my back to save the gear...