One of the prime arguments against S_D was/is the amount of any issue that we post, and the recommended amount is currently a third. If we know of a five page preview out there, how can we reasonably add a further third, which would exceed our target. It would be against the spirit of the rule IMHO.
If the company chooses to post a third of the issue that's their business, but I don't think we can argue it doesn't impact on us.
But I'm sure our Mods will have their own notions about such things and will clarify things as we go along.