A very basic security feature, as every scam dev makes new accounts:

Limit the maximum withdrawal issue for those new accounts to 1 BTC per hour..

This way no scammer can scam for more than 1 btc .. which would make them walk away from bittrex at least.

The Dev here scammed for 20 BTC in a matter of minutes.. Its totally freakin' unbelievable that you (bittrex) allow someone to withdraw more than 20k USD (in btc) in a matter of minutes..

In EVERY security/fraud detection system of the world this transactions would raise like ALL the freakin' red flags of the world...