Given that he is probably the single most recognizable figure in the space, and has been exclusively focused on it for many years, and additionally clearly has the technical skills and people skills to sell it,..., I really don't see a single thing that would make me doubt him being involved in some way.
Did he literally write every last line of code? Yeah I don't know but that sounds unlikely. Is it probably the case that he has some sort of financial stake in launching this, given his position and reputation? Yeah I think so. It doesn't seem remotely plausible that somebody hit him up like a week ago and offered him so much money that he'd be willing to risk the good thing he's already got going by shilling for some product he knows nothing about and has no control over. He is probably reasonably sure that he can influence the direction of the product of he is willing to place some of his own reputation on the line as it appears is happening.
Did he literally write every last line of code? Yeah I don't know but that sounds unlikely. Is it probably the case that he has some sort of financial stake in launching this, given his position and reputation? Yeah I think so. It doesn't seem remotely plausible that somebody hit him up like a week ago and offered him so much money that he'd be willing to risk the good thing he's already got going by shilling for some product he knows nothing about and has no control over. He is probably reasonably sure that he can influence the direction of the product of he is willing to place some of his own reputation on the line as it appears is happening.