I don't trust rumors, but holding a runway inoperative for the AAIB to have a look doesn't sound right.
The only runways that I have come across that were held inoperative awaiting an investigation, had burning aircraft at the end of them and not just for a ho hum engine failure.
In all my experience the airport operator simply cleans up the bits, perhaps with a photo or two and does his best to avoid placing other aircraft in a pressure cooker situation. It's really not a big deal for an investigator to arrive later and have a look at the bits still lying in the grass alongside the runway as well as the runway sweepings. For the more serious stuff a later look at gouge marks can also be made.