Steve Shadders, Technical Director of the Bitcoin SV project, explains:
One aspect of stability is replay protection. Since ABC has not made this stability a priority, Bitcoin SV will do so in order to confidence to users and businesses on both chains. This change will require the Bitcoin SV team to work with the Bitcoin ecosystem, and the timeline will be announced when there is adequate ecosystem readiness.
https://web.archive.org/web/20181126124708/https://coingeek.com/original-bitcoin-reborn-bitcoin-sv-bsv-bch-hash-war-ends/
ABC did actually make this feature a priority, when it implemented the ARP so that the non-upgraded versions (or forks) of its software would automatically be replay-protected vis-a-vis the existing BCH network.
BSV removed this, thereby removing an automatic replay protection which it could have obtained.
Bitcoin Cash clients also prioritized replay protection when they implemented the original August 2017 fork, knowing that they possessed a minority of hashpower.
BSV ignored warnings about not possessing majority hashpower, and apparently wanted to prove a point about what a great event a "hash war" without replay protection would be. Everyone with a bit of common sense and experience told them it would result in a chain split anyway, and at that point replay protection would become de facto available and widely used via new coinbases. As it turns out this was exactly what happened. Eleven days after the above blog post, and no sight of a replay protection patch or even an announcement of the timeline for the BSV ecosystem.
Apparently their Chief Scientist and chief bankroller didn't get the memo leading up to the fork, and their developers also failed to prepare for this contingency - so here we are. At this point, they should bear a lot of responsibility for the "mess" which Calvin Ayre now tries to blame on others.