It seems to be a specialty of theirs, amending the arrival time at the last minute. Although as we've seen in
this thread, they've sometimes not even managed to do so in time for the rail industry's self-imposed "10pm the night before" deadline.
There's nothing wrong with giving people advance notice of a later
estimated arrival, but amending the scheduled arrival time like this in an attempt to minimise/eliminate Delay Repay liability - at a point where most people would no longer have any feasible alternative to sticking with the Sleeper - is fundamentally unreasonable in my opinion.