One thing I like to do with sr+ engineers who will feel burned by a decision - esp. those very publicly against it - is to lead with some sort of concession... maybe a project they expressed interest in, greenlight for a week to research some POC.

Whatever it is, it tends to be considerably less value to the business than the decision itself, but it directly acknowledges their discontent and allows them to get something out of the process besides platitudes, (perceived) public embarrassment, and frustration.