While it does look, at first pass, like a poor design, I don't think any of us are qualified to pass judgement without having actually worked the numbers. Is there any evidence of the posts failing in general use or is this an isolated issue? You mentioned this being an older design, was it updated because of tendency to fail?
Edit: A quick googling on this turns up numerous accounts of the inner block cracking, saddle separation. So we got a poor design or one that is implemented in such a way that the end user is prone to improperly tightening it.
According to their web site "Extensive FEA development". In this case I'm guessing they evaluated what happens after the post breaks.
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.