Hi Deepayan,
You aren't missing anything, this instead shows that with this example, the code is able to index the three category instances of 'red'. This can be valuable if you wanted to change these red categories to a different category, like 'green' or 'blue', or even a new category, like 'purple'. I do believe that the purpose of that example is that the equality now works over the entire array, which is a very nice feature of this category instance.
So it is really much more of a specific case of some relatively unique and convenient functionality of the categorical type in MATLAB.
Best,
Michael
