What is the driving force of Bartoli indole synthesis?

[![enter image description here](https://upload.wikimedia.org/wikipedia/commons/f/f3/Bartoli_Indole_Synthesis_Mechanism.png)](https://upload.wikimedia.org/wikipedia/commons/f/f3/Bartoli_Indole_Synthesis_Mechanism.png)
The Bartoli indole synthesis mechanism begins with a series of attacks on the nitroarene regent by the Grignard reagents. But the atom $\ce{O}$ in $\ce{-NO2}$ should be negative, and Grignard reagent is also be negative, they should repel each other. So, why the first step happens?


I calculate the ESP and the LUMO of nitrobenzene by NBO.


[![ESP](https://i.stack.imgur.com/8qDLNm.jpg)](https://i.stack.imgur.com/8qDLNm.jpg)


[![LUMO(33)](https://i.stack.imgur.com/AVt7bm.png)](https://i.stack.imgur.com/AVt7bm.png)


If it is because HOMO(Grignard)-LUMO(nitrobenzene) is bigger than their electrostatic repulsion, why aromatic nitro compounds perform $\ce{S\_{N}Ar}$ on benzene ring instead of $\ce{-NO2}$?


