I think showing restraint would good, just don't have vote on twenty or more out of 20+1 Blockproducers if you're a top10 whale. How about 3-5, and keep the rest of the voting power for an actual attack scenario.

The problem is once an entity has enough power to vote one person into the top20 single handily, they can practically vote out everyone currently in the top20. The top20 have majority control over block production & rewards, yet the actual voting structure encourages a concentration of stake around that top20.

Irrespective of the individuals involved whether it's BT, or whaleXYZ