The way the study is explained, the control subjects would have had to been explosed to the same situations, including use of emotional language or whatever it was, as the borderline subjects, and a difference still detected. It didn't say that the normal subjects weren't affected by intense emotion, but that those with BPD were more affected.

That physiological differences can be seen says nothing about the cause of the differences. Other studies have shown that a history of abuse shows up in the brain with differences that resemble disorders that are thought to be genetic.

I find studies like this validating because it says that there are legitimate reasons that some things are harder for us. We need to be cautious though not to interpret it as "I can't" control my emotions and behavior. We still can. I would like to see a follow-up study after the Borderline subjects are successfully treated, to see if the same differences show up in someone who was Borderline but no longer meets criteria and/or has learned control.

I also would bet that similar effects would be shown with subjects with related disorders, including PTSD, and any disorders that involve impulse control problems. That woud also be an interesting study.