The text explicitly says that this is an additional requirement. With “hybrid” one pair of atom types can only be assigned to a single pair style, with the other two variants, it can be assigned to multiple. E.g. you could have lj/cut for some and lj/charmm for others and then tip4p/long.
Come to think of it. Using coul/long on some pairs of atoms and tip4p/long on others leads to inconsistent coulomb interactions. Within the tip4p pair style, all coulomb interactions for water oxgen atoms are translated to the point M and the forces projected back. for the pairs where coul is applied the oxygen location will be used.
So from the two options I suggested, option 1. (not to use hybrid) is the only meaningful option. The error from the coulomb by not having all coulomb treated with the tip4p/long part is going to be far larger than the error from using lj/cut instead of lj/charmm.