I love KL more than almost anyplace in the world. :-)
I think that it’s “right” for a nation to set whatever immigration laws it wishes.
I also think that every nation should acknowledge that when they tighten a law, they’re going to catch up in the “sweep” individuals that they didn’t intend or really want to catch.
And that those people should have the right of appeal. And if the appeal is justified, they stay, if not, they go.
I’d also add this: Singapore’s not a place that it’s hard to get a UK visa too. In practice (and I know this is not ideal) the way this would work for her is probably she loses her residency, flies to Singapore, applies for a tourist visa, and is back in the UK in a week. :-)
I assume she just has to fly back every half year or so to renew the visa.