OP’s PSAT score and SI of 210 may qualify for Nation Merit scholarships, so would need to take the SAT to get a confirming score, to advance to finalist status. Taking the SAT may give OP additional options for merit aid through National Merit scholarships, whether sponsored by a college, corporation, or the NMSC.
I do also agree that the ACT is widely accepted by colleges and is not considered to be substandard. Just pointing out that taking the SAT may give this particular student an extra boost for merit $.