Typically, when a user uninstalls the application on their device, and a subsequent push was sent to that device, we will receive feedback from Apple or Google that that device is no longer valid. We will will then mark that device as inactive.
Typically that feedback occurs almost immediately after that push has been sent.
I did do some digging on your account, and I did find some oddities that could be messing with your testing.
Specifically, I found in your Error Console (Located in the bottom right-hand corner of the UA dashboard) that indicates that you have Rejected Device Tokens from Apple. This usually is a result of the implementation for your app. If that is not correct, then we're unable to send a push to the right device.
In order to straighten out that little snag, I would recommend verifying everything in our Rejected Device Token guide before testing out that scenario again.