My reading of jsode's example is in a shared codebase, where it would be reasonable for the person performing the refactoring to update all call sites, and where checking in a change that does not update all call sites to whatever branch is released to production should be unacceptable, as it will provably cause problems in production.

If the change was made in a standalone library that other teams depend on, the type-checker error would be produced when they update the library to the new refactored version, and it's the same story: prohibit deploying known-invalid code to production until you've updated all call-sites to match the changes in the library API.

If updating all call-sites immediately is implausible for whatever reason, leaving the old field in place with a deprecated annotation would be quite reasonable, but the purpose of a type checker in this context is to prevent you from failing to handle this in at least some way. As you say, responsible maintainership of an API should facilitate gradual transition; the use of a type-checker here is to prevent deploying code that will fail at runtime when someone has made a mistake, and can help facilitate responsible maintainership.