As far as I understand how this works, you won't be able to know Bob's source address after he had mixed his coins because the coins will be scattered around numerous newly generated addresses. So the attack vector displayed in your picture is invalid.

The Coinfirm platform will allow for ongoing AML monitoring once fully synchronized with Dash’s blockchain. The platform will provide Dash’s corporate clients, including those who require AML/KYC compliance, with an array of solutions that fulfill and streamline processes. Verification of counterparties, automatic risk assessments, and fraud management tools will be managed and fully scalable by way of Coinfirm’s powerful solutions.

Beyond its use for commercial adoption,Coinfirm’s unique “Wealth Reports” will provide Dash users with the ability to build their verifiable Dash credit history and rating. With an accurate and trusted algorithmic scoring mechanic, entrepreneurs working with Dash will have the incentive and the infrastructure necessary to deploy new financial products and services that will meet consumer demands and grow the economy.