  The Banados-Silk-West effect consists in the possibility to get infinite
energy in the centre of mass frame of two particles colliding near the black
hole horizon. According to S. T. McWilliams, Phys. Rev. Lett. 110 (2013)
011102, the energy at infinity of the outcome vanishes because of infinite
redshift when the point of collision approaches the horizon. I show that this
is not so.
