I would reiterate the reply of Ari Paul stated in the article, 'it may be true'. And the article is staying the obvious.
But how important would that factor be? Especially when all BTC has been mined and nine is available for reward. Would there be enough miners to stay ahead of any potential attacker?

As for the bitcoin and gold contrast,  bitcoin would need a couple more years to mature and consolidate before it could be a fair comparison.