In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
If the guy, who is working for BNP Paribas, does not write or sign or prepare any interest-based contract, the job and income must be halal although he works in an interest-based organization. Rather, all he does is anti-money laundering and anti-corruption, this is great because it helps reducing the wrong and evil on earth.
Almighty Allah knows best.