At the end of the day what anyone thinks is largely irrelevant, as, according to their own tax filings, P&O Ferries does not directly employ anyone who isn't shorebased. So, by definition, everyone who was let go, was employed by someone other than P&O.
Said employees presumably were aware of this, yet suddenly it is the fault of P&O. That's what I meant when I said they should have been aware of something coming. Especially in light of the events in 2019.
It wouldn't surprise me if the agency/agencies they were employed by did inform the government that they were letting their staff go (assuming, of course, that they were letting over 100 people go... the legal threshold), or that they are even UK or EU based to begin with and therefore obliged to do so.
Still a shitty thing to do, but by no means unprecedented in a developed country in the 21st century.