Don't I have a say in the matter?

这事我没话语权吗？

That would imply you had a say in the matter.

那会表示你还有说话余地。

Of course she didn't have a say in the matter.

当然不是她不要 而是没人给。

It's not your job anymore to have a say in the matter.

现在你已经没有责任再为这个问题发言了。

Also, shouldn't those people who don't want human extinction have a say in the matter, too?

还有，那些不想让人类灭绝的人不应该也有发言权吗？