In fairness, it’s less controversial and more that the line is outright offensive. At the time, people were being murdered by acts of terrorismin in the troubles, so to wontonly say that those attacks are effective and will get results was extremely insensitive. It’s sort of like saying 9/11 was an effective use of terrorism shortly after it happened, or the 2015 Paris attacks.
That being said, it’s still an interesting point that Data raises in the episode.