They didn't say they were an old timer. They just used it to establish that they weren't some junior dev whose been using it for all of 4 months but now has opinions we should definitely all listen to.
10 years may not be an old-timer in Emacs terms, but it's well past the clueless newbie phase.
The number of people who have been using and contributing to Emacs continuously since the 80s probably numbers in the dozens if not less. The maintainer of Doom Emacs has been an Emacs user for about 10 years; the lead maintainer of Magic has been an Emacs user for, well I’m not entirely sure, but I’m not aware of his contributions prior to Magit which started just shy of 10 years ago; the maintainer of Projectile has been an Emacs user for about 20 years, and their major contributions started around 10 years ago. If you’ve been using Emacs for 10 years, you’ve probably seen a lot, especially if you contribute to the project. 10 years is a long time in software, whether the project has been around for 15 years or 40 years.
