It's impossible to know exactly what happened without knowing who the sources are, but it sounds like some data was available prior to passage, though no formal report was ready. The follow-up item also carefully declines to stand by the initial assertion that a report was intentionally suppressed or delayed—saying only that none of the relevant data was released publicly until after the law's passage.
The strange thing about all this is that the report didn't actually indicate much that's genuinely new: A similar report by the CMS actuary on a prior version of the bill was released in November, and it, too, noted that health care costs would go up under the bill, that seniors might see Medicare service cuts, and that the increased demand for care could result in a shortage of care providers. That report might have been glossed over somewhat, but it certainly wasn't suppressed.