so if im reading this right,
- you can only stay up to 6 months in indonesia with the digital tax free visa (there's plan of extending it to 5 years, but nothing concrete, just "plan"). You also have to leave and reentry every 2 months. I actually think he's dumb enough to apply for this one without knowing you have to reentry. But generally wayyy too much effort when you can just go to the bahamas or gibraltar if tax evasion is your aim.
- There's the
KITAS visa where you need to be sponsored by a company/spouse/family which you can stay up to 12 months tax-free. But if you are sponsored by a company you have to pay income tax your earned via the company. I doubt he has a family relative living in ID or vshojo having an ID branch.
- If you apply for the
Second home visa (this one you have to pay tax) you can stay up to 10 years. So if he's still in ID after 6 months, he really only came there for the ghost's pussy.

Any longer and you have to renounce your original citizenship and can apply for indonesian citizenship (or getting it through marriage).