It is highly unlikely that any attack could compromise the ability to operate the fleets based at Brize Norton. For example, the length of the runway at Brize Norton is such that it is unlikely that it would be damaged to such an extent that it would be impossible to use.
He is basing that on the results of the bombing of Port Stanley runway in 1982. However, I am sure that if you are going to bomb a runway then the best option would be to fly down the centreline of the runway whilst unleashing your load and not to fly across the runway as per 1982.
However, he is correct. It is highly unlikely that an attack could compromise the use of the runway.