If we ever "lose user account data" and ask you to sign up again (or remove account functionality entirely), then you should not trust this site any longer.
If this were to happen (extremely unlikely), then this site would now be an FBI honeypot.
You would also likely start to see "mods" (not us) encouraging all to post violence.
I believe you can trust this site for as long as your user accounts work, which will hopefully be forever.
Keep in mind that to verify whether your user accounts do work, you also need to check whether an incorrect password doesn't work.
It's a real sad commentary when we don't trust our own FBI anymore, but boy have they earned it. Whenever I hear the FBI is 'on a case', I roll my eyes because I know evidence go bye-bye.