1. ray can swim :yasu:
2. sabaody close to MF so marine n admirals gonna fuck up yonko crew
3. all yonko under heavy survelliance of WG n marines so they won,t go n bet everything to capture rayleigh by themselves
i sure some pirate hunter, yonko agent in grand line or some marines have challenged ray with predictable result
of course king or queen or bm sons can go but the risk they will lose teritory in New World by another yonko or super nova.