They need to clarify that it was a
weak punch
"I could still take all of you and destroy Elbaf"
Indeed Gunko + Shamrock attacks leave Loki to 1% HP or lower. And i doubt they used their most powerful techniques.
Sea stone or not you have to able to take a non-most powerful attack from Shanks inferior and a woman who's tiers below Admirals
and still be at least half your strength especially if you're build like a gigantic 200ft brute monster. The Devil fruit would need to carry his ass, will see