User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-45851841-20200527150344/@comment-24006128-20200527150536

Yup! The read only state is just to make sure that nothing gets added between when we take the snapshot to migrate and when the new version is ready to edit, as those additions would be lost in migration.

If you were to be on a wiki that takes longer than usual to migrate, we would hate for somebody to lose a big edit that they worked really hard to complete because they started after the snapshot was taken.