i'm aware of that design. and it doesn't have the immediate "dump" fail
mode of which jobst accuses it since the post head and the bottom of the
cradle are in compression.

Uh, you mean the compression from the rider sitting on it!?!? That
doesn't make it stable because actually it's under torque... and if
the rider didn't have his weight on the saddle , it wouldn't be a
problem.

Face it, neither you nor Jobst are competent to state the risk rate of
one or two bolt designs. Probably nobody is, as it would require well
controlled actuary data sets with enough incidents to be meaningful.
That leaves only anecdote and thought experiment to persuade.

But why bother? What advantage does a one bolt design have, other
than, "Look Ma! One bolt!", over its obvious drawbacks?

JG