As @o_e_l_e_o wrote the transactions are clearly automated; it is highly likely that no one has intervened manually here. The only question is how this could happen ... a faulty code that only hits after ~60k transactions is of course possible, but especially such highly critical code parts are usually not used lightly in a productive environment.

However, I can't see any intention behind it at first glance, for money laundering or the like the process would be much too delicate. Of course, it is quite possible that the Bitcoins were "gotten rid of", but there would be much better ways to do that.