KeyMaster's was the first post visible, at the time that he posted it, yes. Check the time stamps. His was up before Jason's welcome post.
Was he actually the first post? No, others were deleted as part of the about-to-launch housekeeping. So, as far as visible posts in public areas is concerned, yes, his was the very first.
...too bad it's been his
only, mind, but maybe he just felt like it'd all be downhill from there.