I agree. When I've had a stuck throttle on other bikes, the problem has always been a throttle cable binding.
I'd want to stay away from putting too many lubricants in the throttle assembly because it tends to attract dust and then clog even more. I haven't made it down to the actual throttle on the other end but I've found on my other bike that lubing/cleaning the springs on the carb end (assuming there are springs on the FI end too) tends to clean up the throttle action quite a bit.