I remember Lawrence Miles really went off on The Unquiet Dead on his blog. He truly didn’t like that story.
I think it’s unfortunately in the nature of ’alien invasion’ stories to have the potential for xenophobia– it’s built into the trope at the level of ’alien beings = evil’. That being said I’ve also seen reading of the trope through an anti-colonialist lens. I think it depends on how sensitively the writer approaches the topic.
I still think there isn’t a huge amount of harm in doing a ‘what if the fears are right?’ story or at least extrapolating those fears to an extreme conclusion. It’s what science fiction does.
They’re not fears I agree with but no one is giving Nigel Farage a copy of Flip Flop and telling him he was right all along because Doctor Who says so.
I think writing a twist on an alien invasion where the aliens manipulate the population of the planet is a perfectly valid narrative choice. Where it maybe goes wrong here the amount of ‘this is what the refugees will do if we let them take over’ rhetoric put into the mouths of the Slithergees.
I do think it’s a bit ‘have your cake and eat it’ to dismiss The Unquiet Dead though. It clearly shows the Doctor being duped by ‘refugees’ and could quite easily be critiqued in the same way as Flip Flop is. They’re both versions of the same trope really.
Maybe I’m naive but I like to think that most Doctor Who writers aren’t setting out to promote dangerous political ideas and that most of the time it’s just an unfortunate combination of story elements, audience bias and the change in cultural and societal awareness which makes older stories hit differently. It doesn’t make the people behind them terrible human beings.