Cause and effect chain: loose lug nuts, broken bearing

My car suddenly picked up a nasty thump once per revolution. The tires were fine and I didn’t initially see the problem, so I had it towed into Pep Boys, where I’d had my brakes inspected and tires rotated about a week before.

In the parking lot, I noticed for the first time that the lug nuts on the tire making the noise were totally loose - three of the five could be taken off by finger, the other two were only being held by the wheel leaning out and prying against them - they were far from being screwed in tight. The thumping was the loose wheel slamming back and forth to different angles on the bolts.

It also has a broken bearing on that wheel, and they said they may need to replace the spindle. They quoted me a little over $500.

They say that my bearing cracked and the vibration caused my lug nuts to all vibrate loose. But I never felt any vibration in the car until the tire suddenly started slamming around, at which point I stopped immediately and had the car towed there. They told me it’s “impossible” that they put the lug nuts on one tire and didn’t torque them down all the way, because they use a “torque stick,” which looked like a normal torque wrench to me.

I’m suspicious that they left the lug nuts loose on one tire, and when the nuts finally loosened up enough that the wheel started slamming around at highway speed, even though I stopped immediately, that slamming around broke a bearing.

Any opinions on the likelihood of one sequence of events versus the other? Is it possible a bearing broke, and caused so much vibration it shook all my lug nuts loose without me ever noticing the car had picked up a vibration, even on the freeway? Or did they leave my nuts loose, and when the tire started slamming around, it broke a bearing?

Most of the techs I work with refer to a torque wrench as a torque stick even though a torque stick is like a small extension made of flex steel used with an impact wrench. As for the situation of the lug nuts coming loose I highly doubt that the vibration caused the lugs to come loose, they probably missed that wheel when tightening the lug nuts (maybe the phone rang or something).