Even if it were an external tool, I fail to understand how there would be a legal problem. Companies use all sorts of shenanigans to encourage users to migrate.

Even if it were an external tool, I fail to understand how there would be a legal problem. Companies use all sorts of shenanigans to encourage users to migrate. Immoral? Sure, but software crossed that bridge a long time ago. Heaps of people online have stories about how Microsoft tricked them into upgrading Windows.