You might ask, why anyone would risk issuing an assets, when in case of margin call, they would loose their money. In my understanding the benefit would be a bridge fee as a profit. But is it that mean, that issuer will has to believe, that BTS price will rise? Is it not a too risky assumption for businesses like gateway/bride provider? Exchanges should earn money despite the fact that prices sometimes drops.
Isn't it nearly always the case that you short sell because you think your collateral will increase in value?
In your scenario what if CCEDK just bought 1 USD off the DEX or some other exchange rather than issuing it themselves and then offered you $0.99 bitUSD for your $1 USD. Then they make their 1% spread without being exposed to any collateral risk. They'd also offer to buy bitUSD for $0.99 USD making their spread 2%.