> The imperial boomerang is the theory that governments that develop repressive techniques to control colonial territories will eventually deploy those same techniques domestically against their own citizens.

This is different from what parent post describes. Parent means developing tools by one side of a barricade, that the other may eventually use against them, e.g. when the power shifts to them. Whereas you speak about developing the tools to be used abroad, but those tools eventually also get used domestically, but the administrator remains the same.