Well, here comes images of what I"m trying to achieve.
Original Image:

The goal:

Observation from just 1 splinter

Standard Motion Blur

I can honestly only deduce that splinter use one direction motion blur. I do not know the specifics of convolution other than it goes in one direction only, but knowing the specific isn’t that necessary. As you see in my g’mic thread, that one was done with 2-direction motion blur.
That being said, I don’t like how gaussian command use 11 and 12 as variable. That makes things confusing.