Well they are indication, just not conclusive evidence, since they can be natural or faked (at a cost)
smooth in Bill Clinton mode.
They can also be an indication of deception to confuse when there are actually attacks ongoing, which was CfB's correct point.
But lack of ephemeral forks is conclusive evidence of lack of an attack, subject to the (reasonable) conditions I stated above.
Wrong again. Example, Finney attack. Example, a double-spend that falls within the expected number of confirmations of normal orphan rate.
And censored transactions with ongoing 51% attack where there are no forks other than normal ones with the expected number of confirmations of normal orphan rate.