Answered within half an hour
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So long as the carrier is forward, force on the bolt goes into the frame, and the jarring of any recoil force is not enough to shift the mass of the carrier far enough back to unlock the bolt lug. Not a safety issue. As I'd figured, the purpose of the latch is to allow you to pull on the foregrip for a better shoulder mount without racking the slide back.
Mystery solved
TCB