Older Sister Tickled By College Boy Fetishist

So my older sister who is 36 told me something interesting, so when she was starting as a teaching assistant at 24 years old she had to assist with classes at our local college to get experience, one time the autistic student about 18 years old asked her for help with his science class on nerve endings and apparently he asked to use her feet as an example and my sister being too naive said yes. Only thing is he asked to do it in a classroom privately which she said yes but when she took off her shoes she didn't expect him to also take off her socks revealing her big soles and long toes. She was apparently Abit taken aback but thought it was just his autism but according to my sister all he did was fondle her soles and even tested her ticklishness sometimes hard. He eventually stopped and said "thank you for letting me use your pretty feet miss" she just said "your welcome" and when she went to put her socks back on, the guy stopped her and slowly did it for her. She said it was very bizarre but tbh I found the story sexy