Is Arnone's period of disability defined by section 404.320(a) a "period of disability" excluded from the relevant calculation?

20 C.F.R. Sec. 404.320(a). This provision could operate to exclude from the relevant calculation the years in which Arnone did not work. "The [section] speaks to applicants who apply too late to receive benefits for the period of disability, but who nevertheless wish to have the years in the period of disability excluded from the number of years for which quarters of coverage are required." Sprow v. Bowen, 865 F.2d 207, 209 (9th Cir.1989). If eligible for a "period of disability," then, Arnone might have maintained his "insured status" until or past January 1981, when he applied for benefits.