How would you assign a taxonomy term on user registration programmatically?
Have you considered using Rules?
You could have it react on updating an After saving a new user account,

check for the role being set,

Click on Add Action, select Set Data Value

For DATA Data Selector put account:field-[name] In mine I named/called the term reference field test
For VALUE Data Selector put site:current-user:field-[name]
We use site current user, because the current logged in user is the Meeting Manager, so we use their term ref field value.

Result:
This is how it should look like for you. Except for you the authenticated user in condition should be customer and in Action the test should be your term ref field name.