Google safebrowsing blocked it, so it does not work in Firefox anymore (and any other browser); after ignoring the warning, it's clear that there are ample warnings on the website itself about this being a parody, not to enter sensitive information, etc. I reported it as "not deceptive".
I also reported it safe, as it is still there hours later. There is apparently no way to turn off the use of safe browsing in Firefox for Android, which is disconcerting. So I blocked safebrowsing.googleapis.com. After that, clearing the app's cache did the trick for me.