At any point, anyone with a social mission can lose it. You live and breathe your work. It's so personal to you. Meltdowns like Russell's can happen whenever you have a mission much bigger than yourself.
Imagine for a second your worst day or your worst decision -- and having that magnified a million times. A Google search for "Jason Russell arrest" (which was not an actual arrest because charges weren't made) conjured up 121 million results on Google. Imagine that with your name.