It depends on your way of thinking of course, if for example we want to be a country that can continue to project force and power worldwide then yes that report is correct. What if we don't? what if the public don't really care about the odd Russian sub or a Bear doing circuits of the UK (In international airspace)? what if they're happy and content to be more like Denmark or the Netherlands? prosperous nations that have much smaller, cheaper, defence forces than ourselves?
Who says we have to be the ones to keep the Russians in check, the Syrians and Iranians etc.....? Perhaps the public want better hospitals, roads and schools etc?
Perhaps if we spent less on expeditionary warfare and more on homeland defence we would be less susceptible to homegrown terrorism?
Do we need Trident, could we have a less expensive, less capable but still credible nuclear deterrent? Do we need nukes at all?
When you answer those questions (Good luck) then you can start to worry about a new MPA.