The information from that site is completely WRONG on several counts. Motorcycle oil is in a unique environment where it must bathe and lubricate the motor, transmission, and even perform cooling duties on some bikes.
With this in mind, the companies that make motorcycle-specific oils add a sophisticated blend of agents that assist shearing properties, prevent foaming, and generally increase the protection aspects of the oil. Anyone who tells you "oil is oil" isn't being completely truthful. Using proper motorcycle-specific oil is good, cheap insurance for your powerplant. Don't try to cut corners on the lifeblood of your motor.
~ Blue Jays ~