Thank you Quinn for confirming this is how the system is currently supposed to work. I filed the report you suggested under the id "FB13208662".

Hi Quinn! Thank you for your fast response! I have created a bug ticket as you've suggested. (FB12765973) I assume due to previous communications you have no way to make sure this is looked at by the team responsible for Login Window - but I wouldn't do my duty if I didn't ask. :D I'd really prefer not to have to distribute a new version on day 1 just to fix this issue because it really doesn't make sense to call firstResponder before the view is ever requested from my plugin. :(

Thank you for your reply. I opened a follow-up DTS incident for this post, the ID is 817486166.