What They Mean
"Europe is very weak in the semiconductor business. There are not too many British alternatives outside ARM for them, if they want to continue their specialization".
Moving to Infineon, NXP or STM is probably not easy, given the language and culture barriers. At least not as easy as moving to one of 250 other companies of this type in the SF area.
Of course this line of thinking is a bit destructive. There are probably many computer science jobs in the UK outside ARM. If the chip companies are not interested, there are automotive, aerospace, rail, tool machines, instruments, banking, medical, etc etc.
Politicians here are incapable of replicating the Airbus success story in computers and semiconductors. No Franz Josef Strauss and no General de Gaulle around...
And of course the Americans will try to sabotage it with all of their power instruments from lawyers to defamation experts. Lets see how they reign into Ursula...