I have been looking a bit more into this as I could not believe people actually buying SBD for 22$ and upwards. Just because an exchange is offline that does not mean the price would deviate from the online average.

The situation seems to be like this.

1. Find an unreliable exchange
2. Wait until wallet maintenance, or other reason why you cannot get into or out of that exchange.
3. Start trading between two accounts at a ridiculous price to create high volume at high price
4. Wait for this to show up on online listings
5. Prices on other platforms get affected by this since people sell/buy without checking for the details
6. Sell/buy on other exchanges to benefit from the manipulated price

Lessons to learn,
If you have some crypto on the manipulated exchange profit from arbitrage as much as possible
Before you trust online averages verify your information, especially after crazy price movements.