Direct quote:

It’s speculation, but I’d look for the re-enable event when creating a new user in our DB rather than un-deleting the existing one.

Please stop speculating when talking about an issue. Please take ten minutes of time to track down the source, and see what it could be.

Ready? You can find the actual, non-speculative answer in this many keystrokes in Textmate on a pretty large project:

• Cmd + T → sche.rb → Return
• Cmd + T → alreg.rb → Return
• Cmd + F → unreg → Return

Twelve keystrokes and you are looking at the literal source of the issue.

Speculation is not to be confused with educated guessing. Educated guessing is when, after looking at the source, the developer says that it could have to do with this instance method. Huzzah! Let us dive in and see if that is the issue.

Adding to the confusion of the hunt by speculating only makes me wonder why you are on the team, let alone being trusted to debug issues timely in the future.