That is correct, only the original buyers of BRO in the "coin sale" and the dev team will ever have Bergstake. It is not transferable. You can give a copy of your wallet and private key away, but there is a trust issue involved, that a duplicate was not made and kept.
Given that the essence of bitcoin is asset transfer, it's strange that Bergstake is not transferable in BRO. The cryptographic infrastructure for transfer of Bergstake is in there.
Bergstake is defined as the output of the coinbase transaction. Bergstake is like a bitcoin transaction. can you transfer a transaction? no. a transaction is a transaction. you can transfer coins with a new transaction, but once a transaction is made it lasts forever, it cannot be changed.
Bergstake refers to a part of a transaction, the address of its output. Bergstake does NOT refer to the coins from this output, that would be the stake.
Yes, you can transfer a transaction. This isn't in the bitcoin core protocol, but neither is Bergstake itself.
If you identify the transaction that generates the bergstake by it's scriptsig, you can sign the scriptsig as part of a new transaction. The new transaction becomes the transferred Bergstake.
It's not a leap of imagination here. And not a lot of coding either. All the infrastructure is there.