I suspect the builder is hesitant because he has never done that before and is afraid that if something goes wrong, he will be in trouble. From what I have read, people install this type of floor - floating - themselves (which Iwould not attempt).
I am aware of the moisture issues and I am ready to monitor it.
Since this product - fusion bamboo by Dansk is relatively new - about a year - do you know of any study done to the product, not to its hardness which is very high, but overall performance? In one store I saw a bamboo floor - strand type - cracking slightly... not very appealing. I could see the little pieces that were glued together. Dansk uses different process to manufacture its floor.
Do you have a bamboo floor yourself?