Goodness - I am surprised that un-belted would be safer than shoulder belt but I do agree that is not intuitive to use for the unfamiliar.
According to the lawyer, it really wasn't connected at all, although he doesn't actually admit to that. He says his client pulled down the mini latch from the roof and plugged it into the regular buckle, not into the mini buckle. She supposedly heard a click and figured it was connected. ¯\_(ツ)_/¯
I had a Honda Pilot for 11 years with the exact same system, on the 2nd and 3rd row middle seats. Both of the mini latches never worked in the regular buckles. I just tried it on the Pacifica 3rd row and it went in, but it doesn't really stay and certainly doesn't click.
I wouldn't say this lawsuit was frivolous, she was in an unfamiliar vehicle (an Uber) and shouldn't be expected to know how all seatbelt systems work, but she needs to take some of the responsibility on herself. I, and my kids, all tug on the belts once they're latched, just to test... ocd maybe, but better safe than yadda yadda.... it's just common sense.
On a side note, there wouldn't have been any confusion if the the mini latches were always connected.