Roy,
You are right in that The fixed gear applies only to the drive wheel.
However, cornering at speed involves shifting your weight to the inside pedal
and "coasting" through the corner. You can't do that with a fixed gear.
Since you are not able to coast and shift your body weight to the inside,
you must by necessity corner much slower.
"Wheel hop" would also be more of a problem on corners making it easier
to tip the trike over. I get goose bumps thinking about it.
Paul Patzkowsky