Bernie Sanders will get his reputation ruined because of this, Clinton will give the Republicans fodder as she tries to counter the criticism that Bernie gives her. Now instead of cultivating support, she has to defend herself as a liberal and expose herself to Republican jabs when it comes time for the general election. Meanwhile, the Republicans wont have as big of a shit show as the last two elections, so instead of everyone looking like a fool, the Republican winner will come out stronger for it.
Why wouldn't it be the exact opposite?

Also, I seriously doubt Bernie Sanders cares about his reputation in national politics when it comes to this...