Not only that, Republicans often begin undermining their opponent's reputation from day one, spending nearly four years focused on convincing the public that Biden is ineffective. Now, all that effort is erased at the most crucial time of the election. They no longer have years to shape public perception. This sets the stage for a fairer fight, and Harris is a more compelling speaker than Biden. I believe It was a good play.
Yes, Harris is articulate and assertive. She is clearly a better choice. The public wants someone sharp and focused. While I believe Biden is a capable president, public image affects votes whether we like it or not. Currently, his image has many Democrats feeling discouraged, though they would likely still vote for him. However, I think Harris can change that once she starts campaigning.
He has lifetime Secret Service protection. Would they sit in the cell with him? Any time served would need to be in a secure, comfortable location. It would be a half-assed prison at best.