His link says that the UK made copies, and that private contractors hired by the UK government such as IBM were given access. IBM, and most other firms that the UK government likely uses as contractors, have offices and data centers in the UK.
I didn't notice anywhere in his link that said that anyone moved copies of the data to the US.
But virgin rents that train from a company that was directed by the state to buy it and given a grant to do so. They had some influence over the design styling, but the decision to run 10 coaches at 140mph between London and Glasgow at specific times was not made by them anyway because they have to fit in with all the other services which have to connect to allow efficient transfers. Also, if BR hadn’t been privatised those trains might have been in service 15 years earlier because the technology was developed by their R&D department which was privatised and asset stripped in the 1980s. The tilting technology was sold to the Italian company that makes Pendolino trains.
Something the article completely sidesteps when talking about metals versus composites :-)
Cost versus steel may well have been a factor as well.