I think with autism its good to look at structural and symptomatic differences in the brain. For example, theres less connectivity in autistic brains between hemispheres, so fields inducing creativity, hemisphere connection and new neuron wirings will help that.
At the same time, its good to tackle the neuronal overgrowth caused by it, which the autism help does quite well in.
When it comes down to it, autism is a series of symptoms caused by structural and expressive differences in how the brain operates, so fields that can target dysfunctional genes and epigenetic expressions will go a long way to permanent improvement I believe. I think Rife requencies are a great idea