That's not an argument against determinism, that's an argument that we will never have all of the information required to predict everything (assuming determinism is true).
There is currently no evidence to fully confirm or deny determinism. It's a possibility.
I personally believe we will never have enough evidence one way or the other. I think it will always be a philosophical question.
Rigth. We will never have the evidence needed to prove determinism. Anyone wanting to prove determinism must (i) create a final theory that explains everything, (ii) exactly and instantaneously measure all the properties of the Universe with infinite precision, (iii) introduce all that information in a computer bigger than the Universe to make an exact prediction about the future properties of the Universe, (iv) measure again in an exact and instantaneous way all the properties of the Universe with infinite precision, and (v) demonstrate that the difference between the prediction and reality is exactly zero. Obviously this proof is not feasible; therefore determinism will always remain as a philosophical view.