I would be surprised if the airflow would turn the vanes at all, let alone resulting in any speed which would cause damage. Bearing in mind that the oil is needed when they are turning at many tens of thousand rpm and at high temp.
The flow has got to work its way through the exhaust baffles, up the manifold, through a max of a couple of small valve openings, through the inlet manifold, turn the turbo vanes and presumably out through the air filter.
If folkes have experience of it - then ok - but I would be surprised.
Dave