<p>The scholarship invitations may depend on various things not necessarily in the order you posted. My D’s SAT scores were certainly not way up there, but her GPA was, as well as her ECs/awards, and evidently her essays (given a personal note sent to her by Adcom).
USC generally looks for students who stand out in some way, students who they wish to attract and who appear to have the qualifications to be candidates for the tippy top schools.</p>
<p>Good luck to your son, he has a very good chances to be invited.</p>