Some ASIC miners, indeed, have third-party firmware installed. It allows you to increase the energy efficiency of the device and maximize profits, for which a commission of 2% is charged. Even then, the profitability and efficiency of such a device is much higher than that of a device with the original firmware.
Most of us here agree that "some" 3rd-party firmware out perform the stock firmware, however, I believe Kano's argument here is that these firmware versions violate the GNU General Public License, in fact, the stock firmware itself does the same since Bitmain refuses to publish the source code to "their" firmware, but since Kano allows them to use his pool he must have some weird theory behind why Bitmain is allowed to do that but not the others.