It feels a bit of s stretch to start suggesting that Louis has autism.
He is 4, he got overwhelmed a bit, misbehaved a bit, and was dealt with by his mum.
I think many 4 year olds would have the noise and vibration of the fly past overwhelming, Kate herself appeared to say you could feel it in your chest.
And it wasn’t just the flypast - he had been in the carriage for Trooping the Colour, hundreds of thousands of people shouting and waving flags, his granny’s photo everywhere, trussed up in sailor suit. At 4 it must have been been very confusing.
From what I have seen all three of the Cambridges and the Tindalls and Phillips children were all very well behaved.
PS, My son is autistic