Of all the many, many reasons to oppose a Joe Biden candidacy, the one you articulated is the least valid. In fact, it is extremely offensive and rather ageist. I do not care about the age of a politician or their "generation," I care about the soundness of their ideas, and the integrity of their actions. Placing a premium on finding someone "young" is silly, especially when the candidate who most energized young voters during the last election cycle was 74.
It’s not necessarily just young, but fresh. New leadership is needed, across-the-board, in both parties. I’m sorry, but if two white guys in their late-70s are the best energizing forces for a progressive party heading into the third decade of the 21st Century then there is something seriously wrong with that party’s ability to develop new leaders with fresh ideas and diverse experiences in life. I appreciate the ability for people like Bernie Sanders and Joe Biden to communicate a message and connect with supporters largely because of the type of politicians that they are not, but it is not healthy for a political party to be a gerontocracy largely shaped by people who look the same, have held the same type of jobs for the better. part of a half-century (a job that has kept them comfortable enough to not have to worry about health care or paying their utility bills every month), and have never had to fight for something simply because of the culture they might have grown up in, the ethnicity they might share, their financial well-being or financial weariness, or the opportunities that they might have missed out on or been flat-out denied because of who they are and where they are from. Two career politicians who were born before D-Day are not the ideal leaders for a party that needs to move forward. I do care about the age of the people leading us into tomorrow because I’m tired of being waking up trapped in an endless sequence of yesterdays.