What should I do??

When I waited train at Ryokuen toshi station, disable person was there.
I think he is about 30~40yr old.He spoke something to many ppl.
Most Ferris students ignored or avoided him.
I though he just wanted to greet everyone who were there.
I felt pity for him coz everyone avoided him.
So when he approached me and greeted,I responded.
Honestly, I was scared...but I tried to smile and greet.
He was coming, going and tapped me.
And suddenly he grasped my arm and shook hard!!
I was really surprised and really really scared!!!

When there is such person, what should I do...
Should I ignore?avoid??
I don't want to discriminate such ppl but...mmm...
It's difficult problem...