The turbo is driven by exhaust gases so it can't run if the engine
isn't running.

It can happen to *any* turbo diesel.

If the seals go badly, the turbo will suck engine oil into the intake,
which the engine will then run on instead of the diesel fuel injected.

Because there's no ignition to turn off, and the engine isn't running on
fuel from the injection pump, the engine will run until the "fuel" - the
engine oil - runs out. Oh, and because diesels are throttled by managing
the fuel rather than the air, and there's no restriction on the oil being
sucked up from the sump by the turbo, it'll run at absolute full-welly
until the oil runs out...at which point, it'll be thoroughly nice and hot
and revving its nadgers off...

The _only_ other option is to try and stall it.

Is the Renault/Nissan engine more prone to it than others? Perhaps. But out
of the many reasons to avoid a Laguna, that ain't top of the list.