The water on titan is frozen so I would reason that any acetylene that does form wouldn't do so in high enough quantities to support a large population and without a relatively large population detecting life will be difficult. I'm not arguing that we can easily find life that doesn't depend it's existence in some way on water, you were making the assertion that life cannot form without water and the correct responses to that claim is that life that we're used to cannot be formed without water. This is similar to the debate on whether life needs to be carbon based in which alternatives like silicon have been proposed.