I sometimes find it helpful to reduce specialized terms to their simpler roots.
For instance, alpha emission is really a form of asymmetric fission. And so is neutron emission.
The outcome of a spallation reaction is the emission of multiple neutrons from a (typically) heavy nucleus, which then corresponds to a reduction in mass of the parent nucleus and a certain release of nuclear binding energy. So on first glance, it seems justifiable to consider nuclear spallation to be simply a special variant of nuclear fission.
Any objections to that argument?