I have to disagree. It is about the risk of his counterparties. If their risk is deemed too high, they will start liquidating assets to get minimise their risk.

Just look at what recently happened in the nickel markets on the London Metals Exchange when a Chinese Nickel Producer had a margin call against a $2bn short position.

Tldr: the brokers liquidated their position due to the unnecessary risk of having a margin call over a weekend.