I can't recall ever seeing any indication that Neer or anyone else on FA will remove the dates registered from FA. But the thought to save this, just in case, came to me.
I have no memory if I got into FA's very first incarnation in January 2005. But things were wiped and the site relaunched in December 2005. The wiki says it reached full operational status December 10, 2005. I seem to recall there was quite the wave of accounts. Took me a couple days.