No, arresting former presidents is a bad idea and not in the interest of national unity.
Is your position that former presidents should be completely above the law? If Trump killed his wife, should he not be arrested?
It’s a difficult balance between holding people accountable and not pissing off too many supporters. If Trump were arrested there would almost certainly be civil unrest.
We don't negotiate with terrorists.
The logical conclusion of your argument is that Trump could go on a mass shooting spree, killing dozens of people every day, and we shouldn't do anything about it because his freak supporters would react violently.
Someone should not be above the law just because they're popular among a violent group of people.
That's one of the most revolting things I've ever heard.