It is entirely possible the 'briber' did not know. Companies, particularly startups, tend to assume that the other party will 'do the right thing' and quite literally may not know any better. Ignorance isn't a defense, but assuming that the other party will properly disclose the conflict of interest is not an unfair assumption; that Kail didn't is, frankly, the main problem here, at least with regard to shares.
With regard to kickbacks, I have no idea how it was 'sold' to the startup; for all I know it was sold as a separate entity that Netflix buys from which they have premade contracts for, etc. I wasn't there, but I wouldn't assume Sumo or Netskope are running around offering people bribes. My guess is it went the other way.
They arranged to pay him a percentage of their billings. It strains credulity to think they might have believed it was innocent, or sanctioned by Netflix. We should all be looking at these companies differently now.
My understanding from reading it (perhaps incorrect) was that they arranged to use a third-party reseller that was actually owned by him; the startups may not have known that fact. Basically, that the percentage of revenue was going directly to Kail may have been known only to Kail; that's how I read it.
With regard to kickbacks, I have no idea how it was 'sold' to the startup; for all I know it was sold as a separate entity that Netflix buys from which they have premade contracts for, etc. I wasn't there, but I wouldn't assume Sumo or Netskope are running around offering people bribes. My guess is it went the other way.