My father was 50 when he sired me and 54 when he sired my sister. My sister is a scientist at LANL. She is currently in charge of the world's most powerful microscope. I was 35 when I sired my daughter, she is a highest honor student college senior finishing a double BS degree in math and chemistry. As to me, I am the black sheep of the family, being only a college dean. Granted this is anecdotal evidence instead of 'science' but I still smell a rat.
Surely you realise that your personal account is not only anecdotal, but wholly irrelevant to the accuracy of this study.
Most people do not develop autism. If children born to older fathers have a slightly higher risk of autism, then this means that most children born to older fathers do not develop autism either. If we picked somebody with an older dad at random, they'd be more likely to not be autistic than to be autistic.
And yet I can't see any other reason for the rodent odour. What's so prima facie improbable about the idea?