What he’s saying is that op returns will be more convenient for spammers and said spam can be pruned, a pruned node is not a fully validating node. So hopefully the spammers or attackers will use prunable data. Thats wishful thinking imho.
If spam is the concern we need to fix the segwit discount.
I don’t think spam is the cause for the change in v30. I think this change was pushed bc people want bitcoin to do ethereum like things 🚩
Removing limits altogether seems like the incorrect thing to do regardless, especially if cores intention was to “unify the mempool”.