I'd be more inclined to believe that it's simply to immediately address the current circumstances, and avoid any obvious insensitivities, since the ride's original backstory is about the ride being haunted by a ghost/poltergeist (and the fact it sits virtually back to back with TRR). Same reason they no longer play the Jack Darke audio effects/commentary, and have removed the coffin and undertaker wagon props from outside Eureka. Leaving anything like that post incident would be seen as very poor taste. I don't think it's any indication that a theme change is coming, just stripping back the current one appropriately.
That said, there's no reason why they can't keep the ride themed the way it is without the back story. Doesn't take a rocket scientist to realise that the circular shape of the track resembles a buzzsaw blade anyway, so I don't think people would question it anyway. No more than people not questioning the Wipeout being themed to a giant wave without an explanation as to why.
Just my 2c.