Its a tracker cookie so they know who you are
I am not sure what you can say to somebody that seems know about tracker cookies yet then gets caught out by the use of one.
I guess the point was that he was wrong about his post and thought he could get away with it as there is not a spam verification system to enter this site.
A spam verification system is not putt here as a tracker cookie it is exactly what it is a spam verification system, not a tracker cookie as he claimed. Nearly all membership sites have the tracker cookies in place to control your log in session.