1) President of the FSF is a leadership position.
2) It would take a staggering feat of mental gymnastics to suggest Dr. Stallman's idiosyncratic role at CSAIL -described variously as "visiting scientist"- absolves him of having leadership responsiblities to students.
3) Though I did not go into details at the time, the argument above applies more widely than leaders per se - it applies to people who affiliate with and represent organisations; for example, I think we could probably agree it would apply to television anchors whether or not they led a 'team' of any kind.
Stallman's relationship with MIT (and vice versa) is a public enough role that I've known about for nearly 20 years though I live on the other side of the planet.