There's been much made of the poor communication from Caledonian Sleeper over these pages when trains are delayed. You'd have thought with the ongoing delays virtually every morning on the Northbound Highlander that by now they'd have robust social media arrangements in place to keep both passengers and those picking them up from intermediate stations up to date with developments. Clearly not. This morning the FW service was 2 hours late making it's final destination, the Inverness portion missed out several stops due to being prohibitively late too and yet checking the CS Twitter pages there was nothing whatsoever advising of the delays and even now there's still no a mention. Frankly that is abysmal customer service - it seems like they think if they don't mention it maybe it won't be noticed
I agree with your overall argument, in that communication is paramount, but as I understand it, the northbound Inverness and Aberdeen portions can only skip intermediate stops to save time if they are significantly delayed and if both these conditions are met:
1) The station is marked ‘set down only’ in the timetable (I.e. not Kingussie, Aviemore or Carrbridge, from which day passengers can board to travel to Inverness) and if it can be ascertained on the basis of the passenger list (which the Inverness and Aberdeen sleepers, as reservations compulsory services, have for both seats and berths) that no passenger needs to alight there.
2) The stop is not needed for operational reasons such as crew changes (this rules out Stirling on the northbound Inverness portion).
On the Fort William portion, which carries day passengers, it is not generally possible to skip stops (although a couple of calls on the WHL are by request only), unless perhaps the train is running so late that any day passengers could be picked up by the first Scotrail train of the day without any inconvenience. That said, most stations on the West Highland Line are mandatory token exchange points for the RETB signalling, so the train will need to stop there to exchange tokens anyway. The Dalmuir stop is also needed for the guard change (and Helensburgh Upper for entering the radio signalling system and changing driver). That said, I have known the train to bypass Glasgow Queen Street (by taking the direct route to Dalmuir via the Edinburgh-Glasgow main line and the Cowlairs chord) when running late; perhaps day passengers from Glasgow Queen Street are simply put onto a unit to connect with the sleeper at Dalmuir. Glasgow Queen Street is a pick-up only call and no overnight passengers alight here under normal circumstances.
When I was on the severely delayed northbound Highlander to Inverness on Wednesday morning, I recall that the train skipped Dunblane, Gleneagles, Pitlochry, Blair Atholl and Dalwhinnie (although the train slowed here to allow the southbound HST to clear the single line section). In all cases, the train manager had made sure that no one intended to leave the train at any of those places. We did of course stop at Dunkeld and Newtonmore to allow a few sleeper passengers to alight. The skipping of stops will have been of inconvenience to no-one. I do feel for those picking up delayed sleeper passengers from these unstaffed Highland stations but this is not a problem unique to the sleeper.