Care to share why you don't buy it?

I mean, I don't either but I can't think of a rational reason not to.

Also we should note that it doesn't even really matter if you are running in a computer simulation; your conscious state could be encoded in anything with enough detail structure to represent your entire state for a particular time slice. Whether there is an encoding for prior or latter time slices isn't even important.

Its easiest to work up to this by starting with "mind uploading" and then playing games with the information such as pausing it, rewinding it, removing time slices etc. Thats pretty much the first couple chapters of the novel.