This happens all the time with service based companies, all over the world. It's only when a company has tangible assets worth while. Right now, IB have won no such rights to XF code, thus a spouse or even lawyer, can register the business that is forwarded the software. The developers then work for the entity, they are not owners of the entity. They change the pricing structure into local currency as the primary, not US, which is then afforded currency conversion rates; they host under a UK domain as the primary with only a .com or such as a parked version and well ah... IB would be forced into the UK courts to continue against the software itself, which will not go anything like the US system, as Commonwealth countries do not allow one another to just sue each other for whatever reason. You have to have real evidence before you'll even make it in front of a court to be heard, and normally you'll have to come up with a whole lot of money in costs prior if suing, to be held in trust as the person actioning.
It would get very ugly for IB to do such in the UK IMHO.