Personally, I don't think it's 100% hopeless. It depends on the individual and their aptitudes. Some students barely remember anything they learned in general chemistry, and they still do OK in organic chem. From what the OP says, it still might be best to withdraw and at least take 1 semester of general chemistry.
That being said, I think you can probably count on two hands the essential pre-requisites to organic chemistry. All of them are technically taught in general chemistry, but the emphasis is very different.
1) Chemical equations should be balanced, technically. But organic chemists often do not balance their equations properly! So watch out for missing water molecules, etc.
2) Covalent vs ionic bonding is based on differences in electronegativity. Metal+non-metal = ionic bond (or highly polar covalent). Two non-metals make a covalent bond.
3) Valence bond theory: covalent bonds are formed when atomic orbitals overlap. Technically, they are really molecular orbitals. But this is not so important most of the time, in the average Sophomore class.
4) Definitions of arrhenius, bronsted and lewis acids.
5) Chemical reactions happen because the products are more stable the reactants, and because they are able to happen at a reasonably fast rate. The stability of the products relates to "thermodynamics". The rate of the reaction relates to "kinetics"
6) Formal charge, octet rule
7) Oxidation/reduction and oxidation states.
All of these basic concepts could probably be taught in a single year of high school chemistry. But they really drag things out in high school and go very slowly. There is catching up to do, but not that much. Most of it could be done in context. A full year of college level general chemistry is massive over kill to prepare for organic chemistry.
Of course, if the student wants to understand how the heck we actually know all this organic chem non-sense, then they will need to take college level general chemistry. Even then, it would only be scratching the surface. Then they should also take physical chemistry, and a graduate level course in spectroscopy. But nobody really needs to do that just to pass Sophomore O-Chem.