I agree in that they disempowered their clients by not keeping them fully informed of the situation along the route they were going to be taken.
I suspect that all cruise companies, including Scenic Cruises, have clauses buried in their agreements which entitle them to do almost whatever they want to keep the tour going (safely),
For example in their agreement Scenic Tours T&C Africa 2020 the following is included:
"5.3 If We cancel a Tour, for whatever reason, before departure:
(a) We will use reasonable endeavours to offer You the closest available tour or cruise departure. If the proposed alternative tour or cruise is:
(i) cheaper than Your original Tour Price, We will refund the difference to You; or
(ii) more expensive than Your original Tour Price, You must pay the difference to Us;
(b) if You accept the proposed alternative tour or cruise, Your Itinerary will be amended accordingly and We will give You an updated Itinerary;
© if You do not accept the proposed alternative tour or cruise within 7 days of being notified by Us of the alternative, We will cancel Your Booking, refund to You all monies paid directly to Us and will have no further liability to You;
(d) We are not liable for any third party costs You may incur, which We have not booked on Your behalf, for example airfares or other arrangements booked independently through or paid to a travel agent.
5.4 If We delay the departure of a Tour, for whatever reason, for more than 7 days, You may terminate this Contract and We will provide You with, at Your option, either:
(a) a full refund of all amounts paid to Us; or
(b) a credit towards future tours with Us which will be valid for 24 months from the date You notify Us of the termination of this Contract.
5.5 We will use reasonable endeavours to provide the Tour You have booked in accordance with Your Itinerary. However, due to the nature of travel, it may not always be possible for Us to adhere strictly to Your Itinerary and the Operator may need to make alterations to the Tour or Your Itinerary, before or after the commencement of the Tour. Where, due to circumstances outside the Operator’s control, We are unable to provide the Tour in accordance with Your Itinerary, We will use reasonable endeavours to:
(a) give You reasonable notice of any alterations, but there may be circumstances beyond Our control in which alterations will be required with little, or no, advance notice; and
(b) provide or arrange appropriate alternative activities, transport and accommodation as required.
5.6 The circumstances in which Your Itinerary or the Tour may be altered include:
(a) high or low water levels in any river or canal;
(b) lock closures, unscheduled vessel maintenance or other operational reasons;
© road, river or weather conditions;
(d) national or local holidays affecting the closure of public buildings or attractions;
(e) Force Majeure Events;
(f) emergency events, accidents, injuries or other incidents involving You or other passengers; and
(g) any other event beyond Our control.
5.7 Alterations to Your Itinerary or the Tour may include:
(a) substitution of vessels for part or the whole of a Tour;
(b) cabin changes on a vessel;
© additional embarkations and disembarkations;
(d) substitution of alternate transportation, including the use of motor coaches;
(e) substitution of hotel accommodation for accommodation on a vessel;
(f) alterations to arrival and departure times;
(g) alterations to sightseeing activities; and
(h) reductions or increases in the time spent at a location.
5.8 If We or the Operator substitute any vessel, motor coach or accommodation under this clause 5, We or they will use reasonable endeavours to provide You with a substitution of equivalent specification or quality, but some services and facilities may not be available for all substitute arrangements.
5.9 Any changes to Your Itinerary will be notified to You:
(a) if prior to Your Tour Departure Date, by phone, email or post using the Guest Contact Details or via Your Travel Agent; or
(b) if during Your Tour, personally by Your Cruise Director or Tour Director.
5.10 To the maximum extent permitted by law, You agree that We are not liable to You for, and You release Us from, any cost, claim, loss, damage or expense whatsoever arising either directly or indirectly in connection with any alteration to Your Itinerary or substitution carried out in accordance with this clause 5, including without limitation any:
(a) claim for distress, disappointment or loss of enjoyment arising from the alteration;
(b) additional personal expenses incurred by You, including for food, beverages and personal items; or
© costs associated with any other travel arrangements affected by the changes, including any costs and expenses incurred by You for cancelling or changing those other arrangements or arising from a failure to meet a connection."
So it was legal, but was it moral or ethical? That’s another question.