Tough river decision with bottom set..5/10 NL @ foxwoods

[ArmenH]

Here are the dynamics:
There is a must move game that just broke and an asian father and son get moved to our table. I have never played with either one. Coincidentally, they are seated next to one another...Another player at the tables pulls me aside and says they always sit next to each other every time they play and he suspects them of cheating. Villain is the son and is sitting with close to 8k, my stack is roughly 7k. On to the hand..Villain open limps for 10 folded around to me and i raise 3c3s to 50 on button SB folds BB(father) folds villain calls. Flop comes 10d5c3d villain checks i fire 75 he thinks briefly announces raise and makes it 250. I call. Turn brings a 2s he insta fires 600 into the pot. I call. River 9c he goes all in...Villain??????? I played my hand like a draw, the diamonds didnt get there. I've completely underrepped the strength of my hand also. Anyway I took about 10 minutes before making my decision. I wanted to take as long as possible to see if i could get any physical tells. I asked villain multiple questions and he didnt respond to one while he sat there in a concrete pose not moving a muscle the whole time. Would villain possibly play a set of 10s or 5s this way? is a hand like 64s in his limping range? What does he put me on? Does he think my hand is strong enough to make a hero call on the river? Does he think my draw missed so hes shoving expecting me to muck? Is villain capable of making a bluff here? His father sits there staring at my chips while im taking my time to make my decision...What does everyone think? my river call would be close to 600bbs. Clear fold?