I've wondered that too! Uskate world has some features that are a bit like GOL gliders/spaceships, and I found some settings that I thought were a bit reminiscent of GOL on an extension I did to Gray Scott to add coupled 'history' and 'wave' reagents to it:

https://youtu.be/W6sO8ZkgU9s?si=ESgUWb5OfZ97P2hk

I think universality in RD sims is extremely likely (almost a given) but probably quite hard to prove.. I guess all it would really need is a working/stable basic primitive like a NAND gate kinda thing though?