I can think of a few NITHCo/Translink things which were troubles-related:
The nationalisation of Belfast Corporation's transport department was in part related to the massive financial strain that destruction of its fleet, decimation of evening ridership (not a time to be out-and-about in early-1970s Belfast, not that there was much commercial/social activity going on [unless rioting at setting fire to things was your thing]), and widespread fares-evasion that self-service ticketing coupled with a general low-level lawlessness encouraged; the Northern Ireland Office wasn't prepared to underwrite BCTDs losses. There were also issues regarding serving those areas of greater Belfast outside the Belfast Corporation boundary, which were served by Ulsterbus (with higher fares and lower frequencies, and whose services were restricted within the BCT area) when it would have been more efficient to extend BCT services to the new estates - there were also the potential complications arising from local government reorganisation in 1974 which was to replace Belfast Corporation with an extended Belfast District Council. Incidentally, BCTD did not become Citybus Ltd - although Citybus had been established in readiness for the takeover there were some legal issues that resulted in the BCTD operations passing directly to NITHCo for a year-or-so, after which Citybus Ltd became operational.
The failure of Coastal Bus Service, Portrush - one of two operations that did take over ex-UTA services on the formation Ulsterbus the other being Sureline Coaches, Lurgan [which survived somewhat longer]) - and the takeover of its services by Ulsterbus was due to the collapse in tourist traffic to the seaside resort of Portrush during The Troubles. Southdown, SUT, and Wallace Arnold had all run coach cruises involving Portrush, and providing local tours to their customers (as well as to more local visitors) was what kept the Coastal business alive (most definitely not the ex-UTA bus services).
Ticket offices at bus stations (or Buscentres, we like to call them) were, and still are, a way of keeping cash of buses and keeping drivers safer from attack - paramilitaries need money, every little bit helps, and bus drivers were very vulnerable.
The elimination of double-deck buses from Ulsterbus and Citybus during the Heubeck years. Think about the difficulty of getting a bomb of the upper deck of a bus . . . there are photographs of the RAOC using armoured excavators to lift bomb-disposal robots through the top-deck windows of buses.
"Floor-lines" on the outside of buses. These looked like the yellow coach-line that ran at skirt level on Arriva's aquamarine/red liveries. The were painted to indicate the floor-line in any given class of bus. This was to allow Army snipers to know where to aim if required to detonate an explosive device.
I suppose the continued existence of ticket offices is the thing that now stands out. And now there's much more willingness for Ulsterbus drivers to sell one a ticket on board. As recently as pre-pandemic, even if they were on the point of departure, they'd send one to the ticket office in the knowledge that they'd have been off the stance before you'd made it there.