In direct communication with Caledonian Sleeper Guest Relations, they've been more than happy to engage with queries and assist with all my bookings for future travel.
All that they have (politely) asked is that, just prior to travel, passengers check the latest guidance and rules for that travel - but they have not in any way discouraged me from making bookings that I have put in for August and November Highlander trips.
The only other thing that they mention in correspondence, as I noted upthread, is that the Club Car will be out of use until the end of August unless otherwise advised.
This really mirrors what the airlines are doing; you can make a booking without having to qualify your eligibility to travel at the time of booking, but by the same token you must ensure that you are eligible to travel immediately prior to actual departure.
To this end, most airlines are emailing passengers the day or two before travel, with any updated operational policies and links to government websites.
