Owning production systems means you can't make mistakes and break things. People are already doing what you're saying can't be done, everyday, when they change production systems.
He's saying you should figure out the path from A to B and get there in small steps. And make sure your tests pass at each step. Don't make big changes that are hard to propagate and merge with others' changes.
Basically, avoid the classic "nobody change anything, I'm doing a merge today!" situation.