It's quite simple, with a little thought experiment.
Imagine for a moment that the terrorists... WIN. That is to say, all rational sense is lost, and all the social progress of the past half century is violently thrown back.
Do you believe that you will be able to effectively adapt to this change, or do you think that you will never be truly happy in that environment?
Which would you prefer in that context-- A slow devolution from what we have back to 300AD standards of humanitarian concern--- Over the course of several human lifetimes-- Or a violent, sudden one that happens within a single human lifetime?
Just as you probably would not be able to endure such a rapid change backward, these people cannot endure a rapid change FORWARD.
Again, the cancer patient analogy still applies. You view the status of being tumor and pain free as an inherent human right, if we apply the analogy correctly. You are asking me when it is OK to force somebody to endure the pain and illness of having these tumors. I am answering you the only way I can-- When enduring that pain for a short time, means less overall complication and pain for the patient later.
The "Magical" option of "I wave a magic wand, and the painful tumors magically vanish with no adverse consequences, and this happens instantly and miraculously" is not realistic, and is not on the table.
When presented with politicians that propose social reform, be more selective in how they propose to enact it. "NOW! DO IT NOW!" has been demonstrated to induce radicalized violence in people that cannot adapt to "Instant" change. It is undesirable to me, because it causes long lasting societal problems of this nature.
As such, when I see politicians that propose social reforms, I look at how they intend to enact them. Do they want to start small, and work toward the end goal, allowing the populace time to adapt to the changes-- or do they intend to claim that "loss of momentum" will adversely affect the ability of the reform to come to fruition, and seek to rush ham-fistedly and unsafely to the finish line, damn the consequences--- I choose the slow, incremental change option. I DO NOT ACCEPT the "We are fine the way we are, no progress for anywone, praise jesus!" option.
You keep trying to bring this down to a black and white dichotomy. I can only assert so many times that grey is a valid choice before I start to tire of the questioning.