No, I agree. It's time for them to be replaced.
I went to Sears and the guy there was talking about 'adjusting' them... I thought he was crazy until I realized he was talking about discounting me on a 2nd pair because these didn't make it to anywhere near the tread life. It's never been about replacing the tires (that's a given seeing the pics) but more about maximizing my discount.
Your analysis seems spot on; the fronts are at 6-7/32nds... so I guess I'd be best sticking with the same brand/model tires on the rear since the front ones are staying put? I'd prefer to look at something else given the wear but don't want to compromise safety, or, God forbid, handling!
I can only imagine how often I'd replace 135 tires!
We do not inherit the Earth from our parents; we borrow it from our children