The different authors have different issues with their works. Turnbull, for instance, seems unable to get his head out of the way he wants to see things, rather than what is actually present. On a History Channel documentary from 4 or 5 years ago, Steve Hayes (and a few others) highlighted that, from a Ninjutsu/Ninja perspective, escape was not only valid, it was ideal in many cases. That was followed immediately by Stephen Turnbull saying "For a Ninja, it was kill or be killed!", showing he really had no understanding of what he was talking about. He seems to look at the historical events, and think about whether or not it makes sense to him, rather than if it would make sense to the actual people involved.
Serge Mol, on the other hand, does seem to "get" the mindset a fair bit more, so it's not a case of applying his Western sensibilities, it's more a case of some flaws in the works themselves. For example, his criteria for what makes a "Koryu" system (in his first book) is "...the books discussion is limited to those Jujutsu styles that were founded before the Meiji period,
or to those schools that are legitimate continuations of the pre-Meiji schools." (bolding emphasis mine). This loophole seems to be have been included to allow Serge to discuss his own school, the Katayama Hoki-Ryu, which was reconstructed in the early 90's after being extinct for over 70 years. And that reconstruction was not without controversy itself. A review of the book is found here:
http://www.hoplology.com/reviews.asp?id=4
Another look at some of the issues with Serge's books is the following review by Rennis Buchner, who is himself a practitioner of Hoki Ryu itself:
http://acmebugei.wordpress.com/2010/06/20/the-curse-of-being-a-generalist-a-review-of-%E2%80%9Cclassical-swordsmanship-of-japan-a-comprehensive-guide-to-kenjutsu-and-iaijutsu%E2%80%9D-by-serge-mol/
(For the record, Serge's teacher is Nakashima Atsumi, the man described by Antony Cummins as "the most knowledgable and respected Ninjutsu researcher and historian in Japan".... which is, to say the least, far from the reality).