I think this is just incorrect. You are not obligated to seek treatment for most medical problems[1]. The point of medicalizing something is to draw a line between situations where it would be too soon for medical professionals to step in and when people enter a situation where they may need external help. One of the diagnostic criteria, which this article mentions, is that your grief is disrupting your life - but despite what this article claims they have misunderstood that criteria. Of course grief changes your routines and life. That change only becomes "disruptive" if you feel the change has somehow gone too far or you are struggling to undo it. This writer is doing neither and therefor does not meet the diagnostic criteria for disordered grief. They are grieving normally and the medical literate supports that understanding.
There are of course medical professionals who use diagnostic criteria as cudgels. Trying to force people to become patients in order to enforce their idea of what someone "should" want. This is a problem but it is a problem that the official diagnostic guidelines try to avoid. For those who are interested in this kind of problem with our medical system might look into the professional philosophy of doctors (generally arrayed around identifying and curing disease) and nursing (generally arrayed around making the patient comfortable as possible). I tend to think the nursing model is the more useful and sensible of the two - even though, of course, if one wants to cure a disease a doctor is helpful.
[1] There are very few diseases, such as tuberculosis, where you can be forced to treat the disease.