But born without tusks may be deemed "good" for the survivability of the elephants in the said environment. No tusks = no ivory, therefore minimising the incentive for poachers to hunt them.

My understanding of evolution is the ability to adapt and adjust to the ever-changing environment over multiple generations, and if we treat ivory poaching as an environmental danger, it makes sense for tuskless elephants to pass their genes on.

Yes. It's good to evade a predator. And the process you describe is accurate. But it occurs because the first elephant without tusks happens to live a longer life and prosper and left a large number of descendants just in time when they were hunting by their tusks. It just occurs, it's not a response in the sense of the specie but in the sense of the randomizing events we call world. That's why I said OP is, in the core of his argument, right.

Then the wrong word is "response", not "evolution". Because this is exactly what evolution through natural selection is all about.

Response would be a better wording. Yes, you are right. <<Evolution>> maybe lead you to assume that variation/response seems to move towards something. But, yeah. You are right.