Chris LaCivita, a top adviser to President Donald Trump, insists that Elon Musk will not cut Social Security in his pursuit to limit government because Musk is “not president” and therefore “doesn’t get to make those decisions.

Pinned to the top of Elon Musk’s X account is a six-minute clip of his recent three-hour interview with the podcaster Joe Rogan.

The involvement of Antonio Gracias, an investor who has known Elon Musk for two decades, suggests that Mr. Musk has made overhauling the Social Security Administration a priority.