At the very end of the book "Conviction: The Untold Story of Putting Jodi Arias Behind Bars," the author notes pwBPD "are often adolescent-like, engaging in childish behavior with simplistic problem-solving strategies."
Does that ring true for you? In particular the simplistic problem-solving strategies? 
I haven't come across this in my research and would like to understand more. Please share any research/articles you may have on this.
I would say their 
emotional responses are simplistic.  But at least in my experience, BPDxw's problem-solving strategies were - if anything - overly complicated.  Unnecessarily complicated & conflict seeking... often involving triangulation.
I guess you could put "problem" in quotes, because it seemed very rarely to be an actual problem.