Of course you are the parent so the child needs to consider your rules. Though sometimes certain situations can become increasingly overwhelming for a child on the spectrum or any other mental disability. That is why it helps to explain why you might have a rule, Or both of you could work through a better way to resolve the argument.
The answer is simple. People can project their insecurities on to others, and sadly there are folks out there that fake physical and or mental disability for "perks", thus why for example, it is very hard to apply for special needs adults to get approved under Social Security. Then that is when you'll find "advicates" that will reprimand anyone who does not fit theeir description of disabled.
You should not doubt yourself like that. Like how I was introduced to art, you can start doing abstract or work with stick figure comics. One could even find art in other subjects. If you like math you can work with a system of equations to build graphs. If you are into science you can do an experiment and depending on what the experiment is, you can archive it, and view it as art. Long story short everyone is good at something! It is better to be good atleast one thing than give in.
A great question 😁
Doing any activity that has to do with our helps boost the skills that we gather from the right side of the brain. We use both sides of our brain and nobody is 100% right or left to brain, so there are skills we can always learn! You know how people exercise, whether it be going on a walk, hit the gym, climb some stairs, etc. to gain focus or to relax? It can be the same thing with art. Not confident with painting? That's ok, options are endless, Coloring in the coloring book, cross, stitching, pottery, spray, painting, and so much more. A few skills that could be developed are Developments with hand, coronation, spatial reasoning, color, identification, And that was only naming a few.