I read these threads with a combination of dread and hope. This one has headed in the dread direction unfortunately.
If the MOD are genuinely using Bowtie type methodologies without a proper numeric or quantified assessment they are being deliberately casual and legally non-compliant (suitable and sufficient risk assessment!).
The risk which the previous posts have struggled with have confused posters. With a fleet the risks which must be assessed are the fleet risks - not the individual crew risks. If you have 40 aircraft then the 40 aircraft need to be protected. Protecting one aircraft makes for a 'lucky' crew or two but does not address the fleet issues.
If potential collisions are occurring - and I'll accept that the category or assessment does make a real difference then this is a pretty poor situation where there is an obvious technical 'fix'. Simple cost benefit takes the cost of the modification versus the cost of life saved - severely modified by the ready availability of a technical solution which could easily be incorporated into standard operations.
For training operations to subject aircraft crew to a real collision risk seems to me utterly appalling. Simple procedures could eliminate it. If you decide to operated aircraft in close proximity under high stress situations as a matter of training realism or something similar then sensible engineered barriers become essential - apart it would seem in the MOD .