I haven't rtft as I honestly couldn't 'bear' to!
This is fucking ridiculous.
Playing merry hell?
coaxing and persuading a child?
asking the teacher to let the dragon 'observe' 
going above the teachers head?
Jesus wept, Is it a full moon or something?
The child needs to understand that it is bring a bear, not, bring a soft toy, dragon, fairy, unicorn, sea lion or limpet ffs. It is YOUR job op to teach him this.
I wonder if you would have reacted the same if it was bring a pebble and your ds wanted to take a seashell? Same difference!
DS is sad as he has said he wants to bring toothless to school tomorrow. He can't. It's a teddy bear picnic not a dragon picnic. Our theme is goldilocks and the 3 bears not 3 dragons. Find a bear'
I see nothing wrong with what the teacher said AT ALL.
Get a grip op, What will you do in 7-8 years time when your ds is at secondary doing cooking and is asked to bring in ingredients to make scones? Say 'fuck it' You do not like scones so here is the ingredients for cup cakes? 