Notwithstanding that this is a rumour network, can I suggest some benefit of the doubt is given in this case until more facts are known?
Absolutely.
How do you know that he had not approached this first flight in a thoroughly professional and incremental manner?
Seeing as AVCEN had built the airframe (without engines and cockpit) at least 17 months before the accident, I would say that gave ample time for plenty of incremental tests.
How do you know that he got airborne 'inadvertently'?
I was trying to suggest quite the opposite. The images I showed do not support this "aft-landing gear" speculation. AVCEN's statement ("Our day of success and accomplishment also turned out to be a day of tragedy.") strongly implies that getting airborne was on the agenda.
How do you know that he did not seek advice from professionals?
I cited all the available documentation I could find, where he does name the _other_ professionals he discussed with. Of course, he could have had others.
It certainly does not seem from your post that you know the answers to these questions, so why assume the worst?
In a professional sense, "the worst" losing your prototype, chief test pilot, CEO and majority stake holder.