Flying into Gatwick, we have all sorts of Helis flying around the boundary. Tower always informs us of the presence of the Helis, and I or my Co-Pilot normally try and find them visually and monitor.
I would say that if you had popped you head up earlier/combined with an R/T call, then the visual/mental picture may have helped the Capt, rather than popping up at the last minute and surprising him. If you are behind the ridge, then he won't see your TCAS return till the last minute, hence the fright.
When we know, then we can plan. When we are surprised, the plan element goes out the window, hence the strong reaction.