I tried with my Macbook Pro (2010) and Mac Pro (2009) and this issue is not there. I pair the BD Remote, reboot, sleep and pull batteries from the remote and still I am not presented with a passcode screen even after doing the above. It just automatically reconnects. I even repaired several times to try and it works fine.

Hopefully you can pester Apple for a fix! Their support forums appear to be down as well, no luck posting this issue there.

The only thing I can't test is another Bluetooth dongle. I wonder if you could use an older Bluetooth 2.0 dongle instead of the built-in 4.0 module in the Mac Mini 2011.