Medical & aged care social security costs are tied to deaths of recipients: the bigger the delta between retirement and death,the greater the cost. If the average lifespan grows rapidly, current social security funding will become insolvent, requiring taxes to be raised and/or retirement age to bw raided to leep the current average delta: neither option will be popular with the electorate.
I think you misunderstand the intent behind longevity research and goals: It's to eliminate the senescence period, or to slow everything down if unable to achieve that.
