Agreed... just because a person works for a company, does not mean any country has jurisdiction over that person in a court of law. Even with selling things across borders nowadays through the web, it is very difficult to actually do anything to a person in another country, because jurisdiction is not a right of another country.
I get that XF are playing the game for image and so forth with VB in the US... me personally, I would have told them to stuff it in their backside and I will only deal with the country I am legally bound by which has jurisdiction over me.
The US do not own .com registration. VB can't stop Google spidering a .com purchased from another country, as all countries have access to .com TLD. Even Paypal... they won't achieve much by trying to stop sales through them, because Paypal have a UK branch in which XF can still accept payment via for US customers.
It isn't up to XF who buys their software and from what country they reside. VB can't do a damn thing under such circumstances of ignoring them... it would force them to the UK courts.