What makes a good leader?
A good leader is somebody who is able to facilitate a process undertaken by a group of people, to achieve a particular goal.
People who are good at resolving conflict are good leaders.
Is leadership different for disabled people?
Having a health issue can change the experience of leadership in the sense that people whose lives are marked by certain barriers or access issues may feel that disclosing those and asking for any adjustments to the activity may lower their status as a leader.
Do you think there are barriers to leadership for disabled people than non disabled people don't face?
Yes. Continuing from my answer above, I think that a lack of confidence (due to the fact that for disabled people the world may pose certain barriers to life) may affect whether disabled people see themselves as someone who can become a leader.