It’s not a “perceived risk”. There is a risk.
The only questions (in a coherent regulatory system) are: What are the probabilities of a collision between a HCRPT aircraft and another aircraft, what would the cost be of that collision and what would be the cost of reducing that risk to (e.g.) once in a thousand years collision versus e.g. once in ten years collision, if the latter is ‘unacceptable’ and the former is ‘acceptable’. As alphacentauri has pointed out elsewhere, everyone would like zero risk, but it ain’t achievable in the real world. In the real world, the question is how many millions are you prepared to spend per percentage point reduction in risk.