I want to get some other opinions too. I feel like this is not going anywhere. We have an overpair, playing multiway vs assumed fish who could be easily slowplaying sets and quite unknown tight guy. Do we have so much value here that we can play for stacks? Do we have 3 streets of value? I think maybe not but thin valuebet could work, we get value from weaker hands and if someone raises we can happily fold. This is just basic strategy imo. I'm not scared that we will lose always when we have AA. It is just that we don't necessarily have the best hand and betting small is a better strategy. I don't know how this discussion went to rational and irrational fears and intuitions. Not wanting to bet/call because I will be committed indicates only that our hand strength in this spot is not good enough, not that I'm afraid.
I guess we have to agree to disagree. You can bet big in this kind of spots and I will keep on betting small.