All orphans as the blockchain will reject them until 577850 ... wasting electricity

Not exactly correct.
Orphans are blocks that get accepted by the pool's wallet, but later rejected by the network (because someone else found the same block earlier).
In this particular case, the pool's wallet is not accepting these blocks ever, so it's only the miner's own interface that say's "BLOCK" -- it's never seen by the pool itself.
I do not believe shares can be rejected by
http://dmdpool.digsys.bg with BOO, if they are valid. Most likely the miner is not using Diamond compatible stratum protocol. In this case, one could use the pushpool interface that this pool is running exactly for that purpose: just replace the -o URL with
http://dmdpool.digsys.bg:3345The pool's stratum and pushpool interfaces are working correctly, as miners are finding blocks and the wallet is dropping these on the floor. This will continue until block 577850 comes. The pool has been enabled again "earlier", because I don't intend to stay late at night for this very purpose and I am confident many people would like to start mining ASAP.
PS: The irony being that most of my miner rigs are down for one reason or another.