No. It is a gift-based framework published by the U.S. government under which a successful case is connected to an employment-based immigrant category and remains subject to that category's eligibility, admissibility and visa availability. It is not a stand-alone visa category in the statute.
A framework attached to existing categories, not a new one
The immigrant categories that lead to permanent residence are set out in the Immigration and Nationality Act, and Gold Card is not one of them. The official page describes a program in which an applicant pays a processing fee, undergoes vetting and makes a gift to the U.S. government, and in which the resulting case is linked to an employment-based category under that statute, with the category's own eligibility and admissibility rules still applying.
For a retired couple who do not intend to work in the United States, the question of which category the case attaches to and how its requirements are met is therefore central, and it is a question the official source must answer for their circumstances. What the couple should not do is treat the gift as a purchase that bypasses the immigration statute. Everything else about their admissibility, including medical, security and prior immigration history, is examined as it would be for any immigrant.