This is a pretty essential point that I think changes the calculus of contact quite a bit. A civilisation capable of visiting us at a reasonable expense to themselves would presumably have much easier access to near unlimited astroids/moons for automated mining.

So unless they really prize rare meat or have other illogical goals you wouldn't expect any aliens to visit us until its as easy for them as it is for us to take a transatlantic flight... I wonder if they're also arguing that they should stay silent to preserve our culture instead of curing our diseases etc.