From recollection, that does not seem true at all. All of Musk's initiatives have benefited from his intuitive ability for hip and technophilic branding. See the naming of "Tesla" and "The Boring Company". He also likes to frame his companies' activities in the context of techno-utopian contributions to civil society, and this is nothing new. Outside of the obvious main electric-cars mission of Tesla, they have also built a battery power reservoir in Australia as well as dabbled in solar panels.
As SpaceX, sending a Tesla into space was great PR.
As the Boring company, they sold overpriced flamethrowers as great PR to the technophile crowd.
Whenever a safety incident regarding a Tesla car occurs, Tesla issues a heavy-handed, highly defensive piece spinning their cars to be among the safest, with a constant undertone of shifting all possible fault elsewhere. The April fools tweet sends a sort of "haters gonna be haters" message to his Tesla fans.
So Musk is indeed highly aware of marketing and branding, and this proposal is highly consistent with Musk's branding and strategy. It has the Musk elements of proposals that
1) seem prima facie simple 2) seem prima facie feasible 3) solve a longstanding big or deep problem, that 4) the layman does not think has been seriously considered before as a solution to the problems it tries to solve, 5) where the problem is currently being addressed by a very different solution that seems technologically uninteresting or costly.