I don't think Diwan is in this game to defeat every known virus known to mankind. I think he's in it to take as much money as he can. Sure, he could be fabulously wealthy if NNVC succeeds, but I think he's willing to settle on being very wealthy if it doesn't.
I truly believe, if he thought his own mystical science worked, he'd be plunking every single penny into keeping NNVC afloat. But I think his efficient Theracour 30% money laundering machine, his pretty decent salary, his stock options and his bonuses (yes, bonuses for accomplishing NOTHING!), is indicative, at least to me, that he's taken more of a "take the money and run" mindset.
I think the science, even if it is valid, upon which as a non-scientist I can't really render an opinion, is a moot point.