Earlier quoted context omitted.
My understanding is that permissive licenses (BSD,MIT) can generally be relicensed. For example you can fork a MIT project under GPL. But to do the same for a GPL project requires agreeement from all copyright owners, or just you if you made everyone sign a CLA. This is the whole point of GPL.
Your general understanding is wrong, as there's nothing in either BSD or MIT that allows for re-licensing, and nothing else gives you that right. You can incorporate MIT/BSD code in a proprietary project, but that imported code itself remains BSD/MIT licensed. For many projects, this is a technicality, but no, you can't claim copyright on MIT/BSD code that isn't yours.
> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
> The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
Note the "deal in the Software without restriction" and "sublicense" permissions and the virality of the terms that require the permission notice must be included with all copies.
One problem with this however is if someone has removed the license from the software like what has happened here, then that software really has no license because the license doesn't specifically state that it applies to derivatives. The Apache 2.0 license is much clearer on that subject of derivative works.