If the motor mount bolt really did sheer off he probably hasn’t replaced it because the shaft is still in the hole and will have to be extracted out. If that much force was on the motor mount I’d replace all the bolts and probably the mount as well.
That would make me wonder about other bolts....axle bolts, body bolts, who knows what other bolts that may not have sheered off but are bound up for you too find 2yrs from now when you try to remove something and every bolt you touch the head snaps off.....that would suck. I might would take a socket set and break loose some bolts in various places to make sure they back out okay.
9k sound like a lot BUT it is a 06 with 50k...in my area with a clean title that would sell for probably 12ish. I’d look up retail on it and subtract 1/3rd and offer him that, tell him that’s all it’s insurance for with a salvage title. To be honest he bought it wrecked and salvaged for probably $1500 -$2000 at auction and has spent 4K repairing it. I SERIOUSLY doubt he has over $6k in it. The 9k he threw out probably has a lot of meat on the bone because he knows he will get hammered on the salvage title. If I wanted it I would probably low ball him with like $6500 and see what he replies with...then after a couple days make a offer that is a little less than mid way.
After looking at some prices for 2006 Jeeps....if it really is in excellent shape and mechanically sound with excellent frame work and paint....then it’s probably going to be insurable for around 8k or so....but that’s my area....you need to find out what they sell for in your area.