The idea of bu was that no blocksize limit is needed and that miners and orphans create an emergent consensus.
BSV represents this idea. I can't remember a vote to opt out of this vision, like ABC opposed on bch.
Plus, ABC opted out of the roadmap bu members agreed upon with the vote for the may 2018 hardfork.
Also, ABC opted out from being compatible with the membership vote of bu regarding the november 2018 hard fork.
Despite the ticker symbol bu should never have developed a client for ABC coin.