So in the interest of science I took the risk for you gents and did a summon backing out of the garage while auto opening the door (all the while staring at the back of the car to make sure it didn't start moving too soon).
It actually worked pretty well. The garage door opened and the car probably waited a good 10-15 seconds before starting to move after sending the door open command. I'm not sure, but they probably also poll the sensors and camera to know when the garage door gets out of the way, then wait an additional 10 seconds or so to make sure it gets cleared.
Now, I won't keep the auto opening enabled just because it's easy enough to open it myself, and when I get home the door already opens when I get 10m or so from my house.
But wanted to let you know it did work without any calls to insurance 1/1 times for me...so it's 100% effective by my scientific study