I wasn't convinced by the notion of a mathematical illusion. Physical illusion yes, mathematical illusion, no.
It was a demonstration of a sensory illusion - your senses are deceived into attempting to perceive an object that cannot exist.
Since complex maths must be going on in some sense in the cerebellum in order for accuracy to be achieved in movement and catching etc. I disagree with your maths purely as a conception as well.
Then show me a 'two'. Show me how we sense a 'two'.
We can sense things, and conceptualise them as individual units, multiple counts of individual units and then have a concept that there are two of something, but how do we sense a 'two'?
Fairly primitive animals co-ordinate complex movements - they certainly aren't capable of complex mathematics. What they can do is co-ordinate, which can be simulated with complex mathematics.
People who cannot derive a parabolic arc of an object under the influence of gravity can, nevertheless, catch a ball. They aren't capable of complex mathematics, but they have trained their muscle-memory to co-ordinate with their visual receptors. People don't do the maths to catch a ball, but mathematicians can describe it mathematically.
O.