Good observation! Frequencies above 100 Hz are normally labeled (Globus and Compex) explosive strength training. Any value above 100 Hz certainly still activates fast-twitch type 2b fibers.
However, these frequencies would be further away from the frequencies (sufficient to cause full tetany) of fast-twitch type 2a, and slow-twitch type 1 fibers. So I believe that the rationale here is that it would convert some of those fibers into the higher type.
Research has shown that there is some plasticity in the muscle fibers: if subjected long enough to another type of stimulation they would start changing their properties: capillarization and energy conversion mechanism. A strength and conditioning trainer is the best judge of whether the athlete needs to work on explosive strength.