But now we have the NTSB waffling on the question. What is going on here???
Leaving aside the unauthorised, unattributable, off-the-record statement made by whoever was minding the shop at the NTSB while the investigators were furloughed, the only reference to an uncontained failure was when they acknowledged that they had "received a report" of one.
That they had received such a report was true. The report, though, wasn't.
I would imagine that, as you surmise, very little time elapsed between the NTSB investigator actually seeing the engine for the first time, and his relaying back to HQ that it had been a contained failure.