I see. I don't think the original version of CoreWars had multiple program counters? Got to admit it's been a while.
You're right, the version described in the original article in the Scientific American did not have the SPL instruction, but the first "Core Wars Standard" proposal in 1988 introduced it.
You can see the different versions collected here: https://corewar.co.uk/standards/
The programs that uses the SPL-bomb tactic usually tried to catch all the enemy processes (slowed down to uselessness by the SPL-bomb) in the same place before finishing them off with a DAT.