I too was going to challenge TAB on the tire issue. Having changed and sold tires all through high school, I've probably changed about 20K tires over those years, I might actually know a bit about this issue.
Personally, I've never had a flat that didn't occur in my driveway, lucky me. I could fix it with a plug and move on. If the flat hasn't been driven on, it should be fine unless the sidewall is compromised, then I would replace it or have it adjusted.
When I need tires, I won't replace less than two and I too put the new rubber on the drive axle and for me, that's the front with my sedan and the rear with my truck. I've never owned a 4WD and even though I've always lived in the North or Northeast, I've never needed one. The philosophy remains the same. If I have need to replace a single tire, I will do so but shortly after, I might replace the sister to maintain symmetry. That tire will then become the spare or a loose spare in the garage.
It has little to do with anything other than traction and even tire wear. It's a sales/marketing gimmick when you hear these old wives tales about replacing all four.
Arguing with TAB is a hobby but it will drive you crazy!
Some AWD systems may suggest that all four tires be replaced but the tread depth of 13/32 to a worn tread of 5/32 is a change in circumference that isn't that significant. I could be wrong.....