Agreed. Using these second level pages as doorway pages that redirect to regular content would also be blackhat.
Another difficulty I see with this approach is that getting legitimate inbound links to this content is going to be difficult or impossible.
Check to see where the inbounds to these pages come from. If the pages get their inbounds only from their current homepages, they're going to be severely handicapped on phrases where external inbound links matter.
If they get their inbounds from the SEO company's network, they're likely to be discovered sooner or later. On anything competitive that will (now or later) require trusted inbounds, they're going to be handicapped.
The arrangement you describe is not a model for longterm success... but it might work in a limited way for a while.
[edited by: Robert_Charlton at 7:25 pm (utc) on Nov. 12, 2007]