As President Joe Biden weighs whether to remain in the 2024 race, one of the defenses raised by the president’s supporters is noteworthy—not just because of what it says about Biden’s acuity but also because of what it says about the state of the modern presidency. During an appearance on MSNBC earlier this week, former Obama administration official Jeh Johnson argued that, effectively, the election is about picking an administration, not a president. “A presidency is more than just one man,” Johnson told Joe Scarborough. “I would take Joe Biden at his worst day at age 86 so long as he has peo…