I think the guys tasked with destroying it had more pressing things to deal with than perfectly obliterating it, under fire, in a Pakistan city, at night, with the world's most wanted man (dead or alive) in their custody. I doubt one jot that failing to destroy the tail of a helicopter, no matter how superdupersecret, was on anyone's mind as they exfilled.
As for the guy on the right, yeah it does look like BritMil uniform - from about 5 decades ago!
As for size of the components, I'd imagine that smaller TRBs would require a faster and possibly therefore larger TGB. Maybe that accounts for it's size, I wouldn't say it would look too cumbersome on a 60, if anything it looks too small for a 53.
All personal conjecture, of course !