You should probably ask them.
As far as I understand this restriction indicates the location of your merchant account not the location of you or your company. So you could open a bank account that's a US or Europe based account and use that with Braintree. This should work and should be legal as far as my limited understanding of this goes. Most countries have branches of foreign banks that allow you to do that, so you can live in one country and open an account that would technically work as an account in their country of origin.