There's more to it than just pushing the seat up...
The seat pan is too darn soft/flexible. I think many of us are looking for a redesigned seat pan.
And that you may not get. The MoCo is going to go with, if they go with anything, the cheapest (to them) to fix. They have consistently used inferior, IMO, seat pan material, causing them to be too flexible. Unfortunately with the SERG and SESG seats being a little shorter and not riding up on the tank as much as the stock RG and SG seats, when the pan flexes downward due to the driver's weight, it causes the separation. IMO all factory seats do this, it's just that on most of them, they ride up on the tank enough that when they do "settle" in, you don't see a gap. I wouldn't hold my breath waiting for the MoCo to redesign the seat pan anytime soon.