Is Indonesia big on sex tourism that such policy would dissuade tourists from visiting? How many single men/women could possibly be dissuaded by such policy and to what extent would businesses be affected?
Virtually none, would be my guess.
And when talking about business. Maybe some businesses will be affected by this law. But only part of the business. And because this Law is not entirely new. so actually businesses in Indonesia are used to this. Actually, the punishment for sex outside of marriage in Indonesia is quite light when compared to Arab countries like Qatar, where the applicable sentence is 7 years in prison. Sourch : google
Which businesses would this target? Does a country with a high Islamic population really attract a level of tourism that would no longer exist if sex outside of marriage was banned. If it's longstanding policy for cultural reasons, then it wouldn't make any difference to begin with.