GET. RID. OF. IT.I've been thinking entirely along these lines. I was considering accepting a 125k mile Toyota warranty - but there is the point you raise about denial because of the oil incident, and there is likelihood it will fail outside the warranty period but still sooner than expected. Those are likely both problems way down the road, and there would zero recourse on my end. Essentially I would be accepting all risk and liability for their mistake.
I agree the trade-in option is probably easiest and best for them. I also wonder if the title ends up branded if I force a buyback. They do have an LCLC on the lot I'd be willing to trade for, though I would miss my round headlights and cloth seats.
Part of the annoyance here is part of why I bought the truck I did with 6 miles (2 of which I added on my test drive) is knowing I was buying a truck that was broken in properly to better ensure longevity. My plan was to keep this one a long time, and maybe even give it to my kid when he gets his license (he is currently 7). My efforts picking the right truck and meticulously breaking it in were entirely offset and compromised through no fault of my own.