Use of such is not incompatible with the use of retrorockets.
You originally said, "Use of such is not incompatible with the use of retrorockets. As a matter of fact, the latter are used first."
Just to provide clarity, I was referring to the EDL (Entry, Descent, Landing) profile of Spirit and Opportunity. Their EDL profiles first deploy the airbags, then fire the retrorockets.
Step 12: Airbags inflate
Step 13: Retrorockets fire