I imagine they would counter that the law of universal gravitation is wrong. Although masses attracting other masses can be observed with the Cavendish experiment, and the best counter I've seen to that is a link to a rather insane alternative physics site.
Thankfully, FET is not based on the shortcomings of your imagination. The earth, most likely, does have a slight gravitational pull from its mass. However, as even round-earth physicists will tell you, gravity is an incredibly weak force. It cannot account for the strength required to keep people grounded, that's what universal acceleration is for.
Could you provide me with the ratio of gravity:universal acceleration that keeps us grounded - otherwise your statement is pointless and my question still stands.
Also I think the FAQ may need to be updated now:
Q: "What about gravity?"
A1: In the dark energy model, DE accelerates the Earth and all celestial bodies in the universe at 9.81m/s2. This is commonly known as Universal Acceleration, which produces the same effect as "gravity" in our local reference frame. See: Equivalence Principle.
A2: In both the McIntyre and the Bishop model, the Earth is being pushed up by the Universal Accelerator underneath it at 9.8m/s2. This mediates observable gravitational effects in our local reference frame.
A3: In the Davis model, the infinite plane produces a finite gravitational field with a downward pull. Click here for the mathematical formulation behind this model.
According to your statement, you just proved the dark energy model, McIntyre and Bishop model "most likely" wrong.