I
suspect your gen is accurate 
Last night's 1S25 arrived in Inverness at 13:05 (and the crew would've still been working for a period after that whilst passengers alighted) - so c.13:30 + 9 hours = 22:30, i.e. the revised departure time.
Interestingly boarding will still commence at 20:00 and presumably some staff will be required for this, so does that mean additional cover has been obtained from Inverness-based CS staff to do the boarding?
I'm also wondering why the Fort William service doesn't appear to be delayed departing too, even though last night's service was similarly late arriving and presumably it uses the same crew back to London tonight? 1Y11 arrived at 13:53, so assuming a 9 hour break it would not be able to depart until after 23:00... (not 19:50)??
(Aberdeen is OK as arrived 11:12 and due to leave 21:43, so >9 hours.)