The Stupid Assumption

So I have a three year old whom doesn't talk as much as the academics would like.

My little boy can be vocal when he wishes but I believe he liked to climb inside his head and creat and invent more than verbalize.
Therefore his lack of conversation caused some concern and he was sent for an assesment.The conclusion was speech delayed. I avocate stongly to do the best for my children so was referred to enroll him in a special school. It has now been just over a week and one home visit and I come to realize that silence causes the assumption of stupid.
Therefore I am very annoyed by the assumption and the lack of understanding brillant mind can be silent.
During my home visit, I was asked numerous questions.
Can he dress himself.
Can he brush his teeth.
Can he eat with a spoon.
Can he play with others.
After saying yes to all these in which he does extremely well and has been doing since he was two, I got a look of doubt from the home visitor.
As the visit continued she worked with my son on block building. He uses lego, magnetics and other building materials all the time. This is a strong area for him.
Build a tower of ten to twelve high of letter blocks.
He build it about eight high, than realizing the instability of the base decided to build a thicker base to tower the remaining blocks on.
To me common sence method to problem solving.
To the assesment lady, not listening and following direction. Blocks only one on top one another.
Next task.
Draw a line. My son draws a line and another line connecting the original line, more lines connected with circles and shapes. I know from at home his fasination with pipes, husband a plumber. He often tells me hook pipe to pipe so water goes to sink.The lady again, finds no value in this, put lack of following instruction.
Oh but wait, the lady pulls out 20 tightly stacked containers of the same color. Biggest to smallest. She informs me that most children his age can only work with five at a time.I tell her to go ahead take them all apart mix them up on the table, I think he'll do fine.
She doubts me and smiles slightly like it is impossible.
A bing bang bomb...........my boy has them all twenty stacked and apart and restacked in seconds.
In closing she says that is the first time a child of his age has ever done all twenty in such short a time.
The lady leaves, I look at my son and say.... those that know everything know nothing and smile. My bright boy smiles back.