I believe this guy paid quite a bit over MSRP, which is silly, but at sticker price a Demon 170 was about the same money as a Redeye when I was shopping last September. It was a no brainer at MSRP for someone that likes to race. I don't think you can build a Hellcat for the same price and be as fast and presumably reliable. A Redeye gets you closer, but I've not seen a lot of those live long below 9.50 either, lots of claims that they do though, but then you're back to being the same price anyway assuming MSRP.
I don't think anyone expected 170 motors to have these failures so people buying them would rightfully think it's a low 9 second high 8 second car with a warranty that based on previous models they'd likely never use and the car would have full OEM drivability. These unfortunate owners are put in a bad spot, and probably soured a bit, deciding to drop in the exact same motor they had problems with, or upgrade something to prevent it from happening again. Having one let go at the top end of the track at 140+ MPH is a huge safety issue and definitely gives me some concern.
My opinion is that lack of QA on these has led to machining/assembly issues and you just have to hope you're lucky enough to get a good one. Unless there's a recall of some sort, we'll never know for sure. I just hope mine is a good one. If it blows up I'd probably do something different and put the replacement engine in the corner of the living room as a display piece unless Dodge could show me official documentation that the replacement had been improved in some way.