Reason #1: International reach
Basketball is a universal sport, and the Spurs have a long track record of drafting or signing players from other countries, which has allowed the team to build a sizeable international fanbase over the years. Not many franchises can say the same, and if drafted by the Spurs, Wembanyama could dramatically expand the team's global reach and the NBA's as a whole in much the same way Yao Ming did in the early 2000s.
San Antonio's built-in international appeal is valuable in and of itself. But the Spurs are already well-known in Wembanyama's home country of France because of Hall of Famer Tony Parker, who spent 18 seasons with the team. The NBA plays preseason games in other countries to broaden its international fanbase and maximize revenue. Wembanyama's entry into the NBA will unquestionably help the league achieve those goals.
Given San Antonio is a perfect fit for the French phenom and is already enormously popular outside of the United States, it wouldn't be shocking if the NBA secretly hopes for the Spurs to land Victor Wembanyama.