They are working longer, but more and more people are dropping out because they are older and there are simply more of them. In fact your charts, especially the graph that shows medicaid growth, indicates that we have an aging population and that the number of retirees is accelerating. This is just the beginning.
You're doing it wrong. If the number of retirees was accelerating, what would that look like in labor force participation rates for persons over the age of 65? Are you suggesting that an accelerating number of retirees (people over the age of 65) should show an INCREASE in their share of the labor force?
What the first chart shows is that there is an INCREASE in the portion of working age people who continue to work. A 2% increase from 4 years ago. It's not the other way around. So if it is true that older folks are dropping out, then it is also true that younger workers are dropping out at a faster pace than the over 65 crowd. If that is also true, then it is completely UNTRUE that the reason for the dropping labor force participation rates overall is due to retirements. That would be like saying the reason that boxers develop dementia earlier in life is because they don't read when the larger causal relationship is the friggin head injuries.
Also, Medicaid eligibility is tied to being poor, not being over 65 like Medicare.