They gave up on it, it was damage control. When you have 3 years of pressure that your vocalist is not good enough that's putting a nail in the coffin yourself. If there was any faith in him, they'd done something else, like send Dave and Nicko to solo to give 20-25 minutes break to Blaze and then do something easy for the encore like NOTB (in D) but not Trooper ffs. It could've been salvaged but it wasn't. It would be catastrophic for Maiden to just lose another vocalist at that point, without a certain replacement.