Much here is very good - when obtaining the drug becomes a preoccupation or interferes with normal functioning, it is a problem. However, on the other hand, it is also a problem when people cannot function due to crippling pain. Certainly a physical addiction develops - but while the author attributes personality change, obsession, etc with opiate addiction, he ignores the fact that people in constant pain also undergo massive personality changes, obsessions about their pain, doctor shopping to try any means (surgery, electronic stimulators, accupuncture, physical therapy, "miracle" diets, hypnosis, etc) to deal with the pain.
But certainly, if you or a loved one take perscription painkillers, you should be on the lookout for side-effects and discuss strategies for not developing a tolerance that requires ever-increasing doses.
Not sure what agenda you think you are seeing here. It appears that you read the article through a certain lens. But, perhaps, I can clarify some of your concerns about the article.
The author often used “may” and suggested there might be other causes for such observations. Chronic pain affects personality, which is well documented, but in different ways than addiction affects personality. Where they are similar is the pain-avoidant behavior parallels medication-seeking behavior, to which you referred. Where it is different, however, is when alternative means are suggested but the patient is obsessed ONLY with the drug.
One is focused on pain avoidance, the other, as the author makes clear, is focused upon obtaining the drug. While those can, at times, appear similarly they are distinguishable.