Are there any known details about this deal? It explains the statement about open-source and closed-source development which basically comes down to the old argument that a wise dictator is better than a democracy.
Which deal do you mean? There is none.
As I understand it Thomas Richter proposes that 3.X is licensed from Hyperion and P96 from the owner. Then developer have to adapt both to Vampire, of course getting a "meal" or similar for it. You only get access to 3.X sourcecodes after signing a agreement with Hyperion that you will not contribute to any competing OS, ruling out any MorphOS or Aros devs here and narrowing it to few developers, in fact besides him I only remember one other that seemed to be interested in 3.X and has access. That all looks like a receipt to high costs and high risks because in fact you do not really control the situation.