Bear in mind that with Lauri Love, while the case was lost in 2016 and a judge ruled that he could be extradited, it then went to the high court and was overturned two years later.
In this case, most of the evidence is presumably in the United States so it doesn't make sense for the trial to happen in the United Kingdom, assuming the United Kingdom has the relevant offence too (I haven't looked it up, but I presume it would be breaching the Official Secrets Act or something along those lines).
Obviously, it is more persuasive to have a British national tried at home (especially with comparative legal systems, e.g. the offence exists in both countries) rather than a foreign judicial system. The same cannot be said for a foreign national, especially if the foreign prosecuting authority will have a much stronger case built up than a domestic prosecuting authority could achieve.