Why a gene for the production of a human hormone would be placed in bacterial DNA

I think that the question refers to the artificial placement of such human gene by medical engineers.

The reason why they would do this is that this is a way of introducing this hormone into a human body: it's easy to introduce bacteria into a human body and such a hormone could be inserted through the bacteria.

Another reason is that this bacteria could produce his hormone and then this can be harvested to use in medicine.