The citizens in the UEF have achieved a degree of enlightenment that makes the GTVA citizens seems like dumb, barbarous monkeys in comparison. The ideals they stand for are fully achievable as is demonstrated by their own society, and they are now fighting to defend that.
Have they? What are the Fedayeen for, then? If the UEF is so enlightened and so awesome to live in, what's the black ops group for? What are Durgas and Vajradharas and massive antimatter stockpiles for? Why did the pacifist Elders allow the Solaris-class to be built and armed so extensively? None of these things are needed for police action.
I wouldn't go so far as to say mind control, but I'm convinced there's a dark side to the UEF we haven't seen yet.
Actually, there are some valid arguments for the Solaris project beyond a 'dark side'. For starters, the threat of a future Shivan attack is real; nodes form all the time, and even if a semi-stable node is a rarity, the possibility is nonetheless there, and Vasuda Prime set a chilling example for the consequences of being unprepared.
As for anti-police action: still quite useful. Massive carriers are really helpful in that regard, as you can sortie dozens of wings all over the place and service your fighter complement all in the same place. They also make for geopolitical stabilizers--they're too expensive to churn out in any kind of subtle or ambiguous way; any faction that tries to make a second one immediately becomes very suspicious from a number of angles. And a Solaris is such a powerful strategic force compared to bog-standard Karunas and Narayanas that it makes smaller arms races less significant. It's also a nice psychological aegis--if a big threat were to show up, the Solaris-class destroyers would be a surefire answer.
The technology, science, and experience gains for producing the class is also noteworthy--the lessons learned in so many areas would be valuable.
Could the money be better spent under the circumstances? Sure, you could easily argue that. But it wasn't wasteful even before AoA.
And, of course, that doesn't mean that there wasn't some more discrete or sinister motivations behind it all--just that there are valid reasons for doing it even within the context of official Ubuntu policy.