The news report, which was the first I had heard about the subject, also reported that over the past few weeks the museum had had to call in the EOD teams as it had been discovered that many exhibits did not have the necassary Free From Explosive (FFE) certificates. In particular one 2nd WW German bomb was discovered to have some "material" still inside it.
I think however from the way the story was presented that this was a separate issue from the main closure, although I'm sure that the loss of visitor income would not have helped the cash flow. The Major interviewed indicated that reduced visitor numbers was a long term problem.