Trailblazer rolls in Park??

Son-in-law (traveling salesman) had his Trailblazer backed into the garage to load up stuff to go on the road. Spent 1 1/2 hours with all doors open and radio going (to beat the boredom). Got done, no start, dead battery. Put vehicle in neutral, pushed it 10 feet out of garage and went to get other car & jumper cables. Trailblazer starts rolling down drive, jumps across road, and smacks big elm tree--mucho damage (they live way out in the country, nobody around). He swears he put it back in Park, and that with all the electronics on the vehicle & a dead battery, it didn't go into Park when he put it in park. 2005 Trailblazer, 65,000 miles. Anybody ever hear of this? Or is he just trying to save face so I won't ride him about it for the next 20 years?(which I'm going to do anyway- :-) Thanks in advance for replies.

It wasn't in park. Period

2nd with maxwedge there....had a '71 charger that had a very worn shifter linkage....mine was in park, but parking pawl didn't engage...luckily there was a tree there about 5ft in front of it:crying: