Yes, though in an airliner the EGPWS would protect you in that circumstance.
No issue with turning it on in controlled airspace shared with civilian traffic.
Entering the MATZ is a different matter though.
As I remember it initially the brief was "ignore RA if positive visual ID"
This was then changed to "always obey an RA" which I strongly disagreed with.
The problem is that even a hawk has the ability to operate well outside the limits that TCAS was ever designed to cope with, so often the RA is just wrong.
It was designed for an airliner, not something that can produce rates or turn/climb like a fast jet.
It also has huge protection bubbles, and in my opinion a military pilot has to be comfortable in close proximity to other aircraft.
RAs are reasonably regular at Heathrow when a departing aircraft has a slightly high rate of climb on the SID. It sound like a big deal, but when you look at the separations involved very few would be worthy of comment or even notice in a MATZ.