My first reaction to seeing the news that Keith Rabois was leaving was Square that this was another indication that the MPOS space was getting crowded and heading for a shakeup. After all, margins are razor thin and Verifone had recently sunk Sail.

The second thought was that maybe Rabois and Dorsey had just come to a parting of the ways and Rabois was no longer willing to be number 2 to Dorsey’s very demanding number 1.

But neither guess was right. A sexual harassment claim led to the parting of the ways between Square and its COO. This note from Rabois explains his reasoning.