Only the copyright holder can re-license a copyrighted work. Re-licensing is not the same as sub-licensing. Under copyright law, the copyright holder is granted certain exclusive rights over their work. If the license grants sub-licensing, a licensee can pass on some or all of the rights in the license to a third party.
The license terms for a sub-license must be consistent with the original license terms, although not necessarily the same. The sub-licensor can use different words as in the original license, but they cannot override the terms and conditions that are required by that license. The sub-licensor cannot sub-license more rights than have been granted by the original license.
The BSD 2-clause does not allow sub-licensing. Works released under this license can be included in a larger work with a more restrictive license or modifications can be put under such a restrictive license, but the original license must remain intact.