"Warning: Use of Tor and Bitcoin together may result in additional attack vectors that could compromise your privacy. Do you wish to proceed?"
This warning is incorrect for Bitcoin. The risks described are that it may be somewhat more vulnerable to DOS attack. For wallet users the only consequence is that it might not work and, if they're in a hurry, they might choose to turn off tor and end up with the same non-privacy they would have had if they had not used Tor.
OpenBazaar is offtopic in this thread.