I honestly can't say I am surprised. The N reg route to an IR has received a considerable amount of coverage in the aviation magazines in recent months and I would imagine that the number of G reg aircraft moving to the N reg and staying here in the UK has been steadily rising in that time. Recent events have probably also resulted in a noticeable increase in applications for permission to do training at the DfT.
We can only hope that somewhere in the midst of this review somebody will stumble upon the simple reason that this is happening and that common sense will prevail. All they need to do is to make the IR something that is as attainable (or nearly so) as the FAA version and the flow will stop and even probably reverse overnight IMHO. The specific problem that they need to address is that of requiring people to sit the full suite of 'professional' exams and to attend the ground school. The standard of theoretical knowledge required for the FAA exam is good enough for the nation with the most instrument rated private pilots so it ought to be good enough here.
Speaking for myself (N reg aircraft and planning on getting an FAA IR when time permits) if they were to find a way to solve the IR problem then my aircraft would be back on the G reg as soon as I could get it done!