Agreed. An explicit rule against those is a better direction. Not an absolute solution to sybils but can discourage attempts if submitters are made aware of penalization of such action. Maybe a mix in here [Phase 1] HIP-55: Explicit Sybil Resistance
But with regard to transfers, that’s a harder one to mandate because among family or friends, transferring funds or tokens to swap is a practical method to reduce txn costs.
If it helps, take for example these cases below
https://court.kleros.io/cases/1233
https://court.kleros.io/cases/1235
https://court.kleros.io/cases/1236
https://court.kleros.io/cases/1237