This article seems to be very similar to the first one you posted. Again, this doesn't prove anything but correlation, not causation. There are so many variables involved...for example, a lot of people retire because of health reasons...those same health reasons can cause the person to die shortly after retiring.
Retirement versus working and it's effects are all individual. Understanding how retirement affects a large group of people may be interesting, but it doesn't necessarily have anything to do with how it will affect you.
If you have a stressful, unrewarding, or tiring job, retirement may come as a relief. For this person, not working may be associated with better health. However, people who structure their life and self identity around work may see retirement in a different light, especially if they had to retire because of a company age policy (like in your above article)...Those who did little besides work may find filling time more of a challenge, feel like they lost their identity, and self worth...possibly leading to depression, lack of motivation, etc...all leading to declining health.
People who have a lot of interests outside of work (hobbies, passions, volunteer opportunities), good relationship with their spouse, use there time to exercise more, eat healthier foods, stay active, etc. generally experience much better long-term health.
Also, as already mentioned above...People who retire because they don’t feel well, or have had a heart attack or stroke, or have been diagnosed with cancer, diabetes, or other chronic condition may not enjoy retirement as much and will also show up in study's like the ones you posted showing a correlation between retirement and declining health.
Retirement enjoyment, health, etc...have been discussed on this forum repeatedly by boglehead retirees...the overwhelming majority of them have claimed improved health, well being, happiness, etc...being prepared financially and emotionally for retirement goes a long way in enjoying a healthy happy retirement.