Now, what position they held definitely will make a difference. But the reason they're not specifying it could be to avoid any violations of employer agreements they had at Apple.
For example, saying "I've worked on the mac desktop interface team and know the architecture and worked with the codebase for X years so I can implement the same (proprietary) architecture" would cause trouble, Obviously they won't be as blatant as this, but it is better to occupy the vague corner and still reap the ex-apple recognition.
This is very obviously trying to feed off Apple's fanbase.
It made me do a double-take when I saw the Windows logo in a screenshot as Apple would never market that, not that it is a bad thing, just that the branding of this app's marketing strikes too close to Apple's.
But who were they at Apple and what did they do there ? Does Apple endorse them in some fashion, do they have privilege access to some technologies ? In what fashion is that relevant ? Outside that branding, there is nothing in there that back that claim with anything concrete.
There is nothing wrong and the application can be indeed great, but this marketing tactic raises all my alarms. Without the positive comments here on HN, I would not even have considered trying that product at all.