Why would I be lying about this? Google doesn't know what to do with the document as downloaded, so it's attempting to open Google Play to find an app for it. Since I'm not logged into Google, the Play Store app jumps straight to the Google Login page on my device. Trying to jump directly to the page in Fennec gives me the Invalid Format error.
Recognizing the file extension of the downloaded script should be HTML rather than PDF, I renamed it as such and loaded it locally in Fennec, where indeed it asked if I'm over 18, but since the page was loaded locally, the Yes/No buttons don't even work as they're sending the button response to localhost 127.0.0.1 instead of their website.
Anyways, thanks for all the help, you've been none.