> This is incorrect. The pound is a unit of force, similar to a Newton. The pound-mass(notated lb-m) is similar to the kg.

That's the pound-force (lbf).

Pound and pound-mass are aliases. Indeed the official facts sheet defines the mass of the rover in kg and pounds.

> The conversation you gave above is based on Earth gravity for weight.

My comment is based on mass being an intrinsic property of matter, gravity does not enter the equation.