In a lot of situations, no additional time is spent (and thus wasted). This happens with advisors in the general case too: they become an advisor and never meet again.
I guess the company should just do that with every former employee? I mean, why not.
This is the behavior of a person and company playing startup and not actually trying to build a strong company.
Like when Carl Pei left OnePlus, we all knew it would go to shit once Oppo took over but they kept up the pretense for a while to protect the brand before they started undermining it.
For the 'advisor' there's probably a financial arrangement to this to keep them quiet and from shoveling up dirt in the media. It's hard to just give someone money like that so again a fake role comes in handy.