The question I'd have is why should the welfare state prioritize able-bodied workers just because they hit a fixed chronological age?
I can definitely understand social security (which is essentially a welfare program) existing to support those who are too frail, infirm, or sick to work. Which would disproportionately fall upon the aged. But if somebody turns 65 and still capable healthy and capable of working (as many 65 year olds are in this day and age), why is the public budget subsidizing that person's leisure?
I also understand the value of retirement as a time in later life to reflect and relax. And if this is valuable to someone they should take the personal initiative to save and invest to fund their retirement. But it doesn't seem like the purview of the welfare state to subsidize this lifestyle. The government doesn't subsidize vacations, gap years, and other types of "reflective leisure time". The purpose of the welfare state is to protect people in the most dire straits, not to make sure everybody's living the most fulfilling life possible.
Heck, I can even understand advocating for UBI, which would give everyone a fallback option to not working. But it simply makes no sense that we essentially have UBI for able-bodied workers who are 65, but not those who are 35.