Ehhh, not really, I have been loosely following him for a while and he is overall pretty genuine (i.e. laser focused on his health experiment above all else)
He was the founder of Braintree which sold to paypal for $800M. He then was divorced and listless with near infinite money, so decided to see what would happen if money was no object and you tried to live a perfectly healthy life as dictated by current medical research, and document it.
He does sell supplements and now whatever immortals care is, but I can't imagine he makes much money from either compared to his NW (and passive income from it). It's more likely that there is demand from people following his experiment to get in on his findings (which are all public anyway, but convenience is king), because again, he doesn't have much incentive to scam people and his goal is already a selfish one, to live forever. But at least he openly shares everything on that path.
Edit: Since people really snag on the money part, since money makes you evil by default, let me rephrase:
"Bryan Johnson, a greedy billionaire, has totally fucked up his latest scam, and you can easily copy everything he does because he foolishy doesn't even try hiding any of his routines, regimens, daily meals, or even obfuscate any of the ingredients in the supplements he sells. That's right, you can fully copy what he does without giving his greedy hands a single penny. He even accidentally shares all his medical findings publicly too."