We don't have an untouched test unit so I can't be sure what you're seeing. The test unit we have was enabled for that feature and we performed it years ago. Once you do it, that's it. The player really doesn't ever need Panasonic central to do anything further.
Have you tried just skipping that step? It might work on the latest firmware given they eliminated the other path.
In the event a fresh unit no longer allows this, the good news is that there is a path. The bad news is that the technical skill required to flash firmware on a player may be beyond some users. On the Internet, you will find widely available firmware improvements for these players which now support all the models and the latest firmware.
One of those changes eliminates this whole issue. Roomie's latest release provides a switch in the Advanced panel of the Devices editor for the Panasonic BD players to turn off Panasonic Authentication in the event you have applied such firmware changes. Not only is the whole voice control registration nonsense eliminated, but control of the player is faster because the pointless auth round trip is eliminated. Note that beyond noting the existence of such things, discussion of how to apply or where to get such things should be avoided here as it's not the right forum for that and it's very easy to find on other well known forums.