It is a question that has been bantered about for a while. I feel, if it fell within the Lord Lyon's jurisdiction he would, if he so wished, be able to do something.
If it was a Scottish company trading 'bucket shop arms' for example using a US server it is still a Scots company and if it was a US company using a Scottish service provider, I am sure he would have reasonable power of persuasion for them to rethink their policies.
No matter what you do though people will still try and exploit any loopholes they can find in order to dupe the public and try and make them believe what they sell is genuine.
At the moment we have companies selling fake Scots titles Such as 'Laird of Glen Cairn' or Laird of 'John O' Groats' http://www.scottishhighlandtitles.com/index.html
selling you a square metre of turf in some remote field and telling folks they can call themselves Lady this or Laird of that.
They get round it by saying they make it clear that it is only a 'gift' or 'novelty' trouble is some take it seriously not knowing any better. However, bringing these people to justice is no easy task and is a costly exercises for the Lyon Court and as you have quite rightly pointed out with the growth of the internet and peoples increased interest in their genealogical roots and so called 'family crests' the battle has increased 10 fold.
John A. Duncan of Sketraw
The Armorial Register - International Register of Armshttp://www.armorial-register.com