Yes, a Government can confiscate a vaults holdings at some point, but you make it sound like they are omnipotent in their ability to strike everywhere, out of the blue with no warning. They can't strike everywhere at once. Unless your vault happens to be unlucky enough to be the first one to be victimized by confiscation, (COMEX and LBMA vaults would be the first hit), the bullion industry will have plenty of warning that confiscation is taking place. And I'm sure businesses in the bullion industry will have plenty of time to notice the political winds of change becoming hostile to their business interests.
In the case of Kinesis, if they come to the conclusion that a jurisdiction in which they have a vault has turned hostile to their interests, they will move the bullion to a different vault in another country. And as a final backup they are insured. And as they are incorporated in a VERY business friendly jurisdiction, I don't think the insurance money is going to be seized.
You would have to have pretty much all Government jurisdictions decide to seize PM's everywhere at the same time. Given that is unlikely to happen, I'm reasonably secure in the ability of Kinesis/ABX to provide a safe and reliable, audited vaulting system. ABX has been doing it for over 10 years.
But, then again, the sun may shoot a mass coronal ejection at the earth, causing hemisphere wide blackouts lasting for months. Or the earth may be struck by a huge asteroid, causing an extinction level event, so why even buy PM's? The point being, the you and I, businesses, Kinesis/ABX, can only take reasonable precautions against foreseeable events that may have a reasonable chance of occurring.