This is your general reminder that the 'rules' about past statements and such are different for private citizens than they are for public officials. Things we might swiftly forgive in a private citizen might still render someone unfit for public office and are thus newsworthy.
For sure, though I'd add that parties are coalitions held together by all sorts of different things and with different sorts of folks. I wish democratic leadership was more effective at loosening some of that coalitional glue, but they are focused on their own fraying coalition.