Reality check needed

Laurie Penny has written a piece for The Guardian's comment Is Free that has some comments in it that I would find risible were they not so dangerous. The piece is about squatters in Saif Gaddafi's London home but the wider points Laurie penny makes are frankly so wrongheaded:

'With ruling elites across the world ensuring there is no room for the young, the poor and the unemployed in their own cities, the drive to reclaim space has now become a global movement.

...

Squatting empty buildings is legal, although the government is keen to criminalise it. It is also a reasonable course of action in a country where almost a million properties are empty, and a million citizens are homeless or precariously housed.

...

The occupation of private property is one of the proudest traditions of resistance in Britain. In 1649, the Diggers occupied St George's Hill in Surrey, declaring that they would no longer allow landowners to fleece the poor. "By theft and murder they took the land," sang the Diggers. Watching protest banners flapping from the window of the Libyan dictator's occupied mansion, those words echoed in my mind.'

The trouble is that the people whose houses have been 'squatted' are not dictators sons or filthy rich, some are people who have purchased a house and are doing it up before moving in. Should they not be allowed to leave a house vacant whilst the builders and decorators are in? Is there a maximum time that they should be allowed to do this before it becomes available to squatters? Who decides the right length of time, Laurie Penny?