Unfortunate - sorry for your loss!
I have to say, in several years of using BR straps (I have a couple of them), I've never had the carabiner locking ring come loose. I did have one camera drop incident, but that was due to an inadvertent press of the lens release with the strap attached to the lens (and that was due to an unbalanced rig with a 2x TC when connected via a FastenR-T1/RC2 plate - switching to Arca plates and a Kirk 1" clamp on the BR strap allows me to balance appropriately).
I have had a the carabiner completely separate at the hinged portion, although my camera did not drop to the ground. BR sent me a replacement carabiner no questions asked.
I too use the Kirk 1" clamp and it is very solid.
There is no doubt in my mind that the weak link in the system is the swivel joint in the BR carabiner assembly.