I have two concerns.
First, expansion plugs work best when they contact a large area of the "pipe" to be plugged. The fuel tank is very thin and leaves a minimum of surface area for seating the edge of the plug.
Second, is the rubber material of the plug fuel resistant, especially fuel containing ethanol?
You might want to try and heat the tank around the screw with a heat gun (no open flame) and use a vise grips to turn the remaining screw out.
Good luck.