Is this what you are thinking of? "Bizen also does not suffer from CMOS’ electrostatic discharge (ESD) susceptibility and latch-up problems."
I bet it does suffer ESD issues. Even “SWR proof” RF BJTs are fragile. Anyway not that it matters really here even for CMOS as the ESD protection is just on the die lands. Most of the devices on the thing don’t have ESD protection on CMOS.
I think the question is about gate charge.
And I guess gate capacitance may cause signal-delays.
Not just delays. Being able to drive a transistor fast can be important for reducing power dissipation. That is, for switching one wants the transistor to spend the least amount of time in the non-saturated (linear) region where it acts as a resistor.
Judging by the process size quoted in the article, they won't be chasing speed, but rather low-cost devices.