Give the guy a break, he has a point.
Hydraulics are extremely, terribly inefficient. You're not getting even remotely close to your engines power rating at the ram on a hydraulic splitter. Without doing any calculations or anything I would take a guess that you're getting less than half the power. Also, with gas engines, you don't get a whole lot of torque rise as it "bogs down", and at a certain point, the torque begins dropping again and the engine dies.
With an electric motor, the torque continuously rises until the motor stalls completely. Torque is what it really doing the work (HP is just a combination of torque and rpms), so with the torque-rise of an electric motor, combine with a gear & screw mechanism (much more efficient than hydraulics) you're getting a lot more of your power at the ram.
Would this splitter compare to a 35 ton hydraulic? Probably not, but I'll bet it could do a pretty good job of keeping pace with a 15 or 20 ton, especially since it splits both ways. Just gotta get somebody that knows what they're doing running a two-way splitter (unlike the person in the video above).