The simplest explanation of why it's wrong is that it's Deterministic. i.e. it's part of the "Clockwork universe" and if that's true, then you do not have free will and we should all just throw in the towel now...
While we're at it, the Second Law of Thermodynamics must be wrong because I'd like a perpetual motion machine and conservation of momentum must get temporarily suspended when someone's about to be run over by a truck.
Also, determinism doesn't conflict with free will. Determinism is a concept in physics and free will is a concept in law and philosophy. If you try to contrast them, you'll end up equating free will with randomness: you didn't write your message based on your beliefs which you've formed based on your character and experience (since that would be deterministic), but rather it's the equivalent of "cat
Determinism = fail
No, but even if it was, it in no way would disprove it.