Hi, I seek for advice. and also maybe warning case study to all of you.

My friend travelled in Phuket. He matched a girl from Tinder. There it does not mention age.

When they met, he asked her age, she said she is 22yo. They hanged out a few time. She asked money for by bikini once. And they had sex one time. When he does not feel right about asking money, he tried to fade out. Then one day she wrote him she is actually 17yo, and that's against the law in Thailand considering having sex with minor, and asked for 5000 THB not to report to police. He paid her, and she blocked him. My friend goes to tourist police, and he was advised to leave Phuket for now. He flew to Bangkok. It has been 2 weeks since the incident. Yesterday she unblocked him and sent 'hi', and cancelled the message. Now my friend is very stressed because he actually paid rent in Phuket for 3 months but he does not dare staying there being afraid that woman will come to blackmailed him again.

To be honest, with photo she looks older than 17yo. But who knows make-up can make u look aged

What should he do?

Edit* : More Information :
It is tourist police is not 'real' police. They act like coordinator or giving advice to tourist in general topic. The one who gave him advice is even a westerner. They say Thai police are normally back up the local. So he even does not believe in the system.

FYI:
She said she is half Thai-Morroccian living in the boarder of between Malaysia and Thailand (Narathiwat)