A stronger Britain and the strategic calculus of Vietnam

Would a non-declining British Empire force the United States and Soviet Union out of Vietnam?

It might prefer to let Vietnam absorb American and Soviet resources that would otherwise be available elsewhere.

A non-declining British Empire would still have to decide whether forcing the superpowers out of Vietnam served its interests. American and Soviet commitments there would absorb resources unavailable elsewhere. That could make continued involvement by both rivals advantageous to Britain. The calculation is explicitly condemned as cruel, even evil, while being treated as an incentive governments could act on.