...to distribute or communicate copies of the Original Work and Derivative
Works to the public, with the proviso that copies of Original Work or
Derivative Works that You distribute or communicate shall be licensed
under this Transitive Grace Period Public Licence no later than 12
months after You distributed or communicated said copies
It looks like the effect is that the public versions must always lag a year behind the proprietary versions.
So, this isn't open source, although it is abandonware protection.
...to distribute or communicate copies of the Original Work and Derivative Works to the public, with the proviso that copies of Original Work or Derivative Works that You distribute or communicate shall be licensed under this Transitive Grace Period Public Licence no later than 12 months after You distributed or communicated said copies
It looks like the effect is that the public versions must always lag a year behind the proprietary versions.
So, this isn't open source, although it is abandonware protection.