Look at this from David Kosch's point of view...
Kochie has a long history in financial services and has seen the Henry Kayes and other property sharks in the past. He's seen the groups flogging crap properties at inflated prices whilst claiming they're a bargain. He's seeing Nathan recommending 20 properties to Nicole and charging $10k each.
Put another way, Nathan has charged Nicole about $200k and other than a statement that they're all bought below value and are neutral to positive cashflow, there's nothing else to support that these are actually good investments. There's no evidence in their statements of prudent risk management. The word strategy is spoken several times, but nothing is actually detailed. Nathan actually doesn't have a license to give financial or credit advice either.
From David's point of view Nathan is potentially a very nasty shark and in the current hot market, the environment looks like Nicole is going for a swim in the open ocean after slathering herself in tuna oil. I doubt David would encourage any of his views to work with Nathan.
Don't get me wrong, I don't believe Nathan operates in this manner at all, he's to be commended for a lot of good work that he's done. However he is operating in a manner that can look dubious when observed from a certain perspective.