That's quite a stretch.

I have a user who uses frequently one specific website and for no apparent reason Firefox decides to tell him it's now dangerous to use with fearful and technological terms (vulnerabilities, plug-in, risk, etc.).

If Mozilla decides its users are dumb and should not be trusted to allow Java applet to be run then they should not warn them with techno-cryptic messages they know their users can't understand (because if Mozilla thought they could then Mozilla would know users could make the difference between a good and a bad applet and that warning wouldn't be needed).

A shorter and less scarier note would have been a better message for everyone.