I recently followed a link to The Overflow, which I suppose is a post from the old blog:
The post's author is:
I was first of all surprised not to see the Coding Horror illustration as the author's avatar.
But even more-so at his title "Co-Founder (Former)".
I would think that a co-founder would remain a co-founder, even after they cease to work at the company.
Here are some relevant posts on English Language & Usage:
When adding the jeff-atwood tag to this Question, the tag description text is:
Co-founder of Stack Exchange, but no longer works for SE.