What kind of political views does she have that everyone is so opposed to?
In her books, she tends to promote a libertarian/conservative agenda. The most blatant case is the New Earth series, about a bunch of libertarians who have decided that they don't want anything at all to do with the big government approach of the Federation and Starfleet, so they get the Federation and Starfleet to protect them while they travel to and establish their distant colony planet where they can live without the oppressive domination of the Federation and Starfleet.
Ironically, like so many anti-government conservatives, she loves everything military, and she supports the American invasion of Iraq -- though traditionally libertarians have been opposed to foreign entanglements. But then, by the time she was running for the Michigan state legislature a few years ago, she had posiitoned herself as a more conventional Christian conservative. Libertarians often have issues with the Christian right's willingness to have government act as an enforcer of morality, but Carey started parroting Christian conservative policy on the importance of Christianity and the evil of abortion, etc.
(FWIW, I'm not anti-military; my parents are both ex-Air Force, my best friend is serving overseas right now with the Army, and a brother-in-law of mine is also in the Army and has served tours in Cyprus, Bosnia, and Afghanistan. But I'm not any kind of conservative, or Christian, or American.)
Whether or not you happen to agree with it, a libertarian/conservative backlash IS a reasonable political development to expect, as the government takes increasing control over society (a move that very likely occurred during the transition from 23rd to 24th centuries, judging from the progression of Federation culture in that time). As such, I see nothing unrealistic about the Belle Terre expedition and the attitudes of the people who run it and to my mind, Carey picked the appropriate setting and plot to express what was on
her mind. The context made sense, and since it made sense, I do not think dismissing it as bad writing simply because of a disagreement is legitimate.
After all, if your objections are that strong, a societal movement of that magnitude, you're really left with three choices: accept it and live within its bounds and keep your grumbling private, overthrow it, or get the hell out of Dodge. In our current world, the first two are our only real choices (with "overthrow," of course, confined to the symbolic overthrowing of free elections). But in the
Star Trek universe, with so much unsettled territory, self-exile once again becomes a viable and in many ways preferable solution as it was for the colonists who ran away from hostile governments to found the colonies here in the states. (And some of THEM then ran into trouble in their burgeoning societies and founded NEW colonies in the Americas. See Rhode Island for one example.) Getting the chance to live as they see fit, under the system they see fit, makes a great deal of sense and one would expect, if the Federation still retains the proper degree of freedom, that people can voluntarily leave if they don't like what's going on.
(This may also go a ways towards explaining the degree of conformity seen in Federation society and Starfleet...those who have severe enough gripes tend to leave rather than put up a political fight.)
As to libertarianism, it comes in different shades, some of them going all the way to anarcho-libertarianism in which there is not a real government to something that simply advocates small government. Under the second version, a military CAN be a legitimate purpose of government, as is infrastructure, and this is what the Belle Terre colonists seem to be thinking. They're uneasy with Starfleet since it isn't under the kind of governmental system they would like it to be, but the fact that they're libertarians does not
necessarily mean that they should see no role for a government or a standing military.
One final point. I do think that authors should be free to have their points of view. All entertainment, or science fiction, heck, even all of
Star Trek should not have to be liberal; in the case of
Star Trek, while there is a lot of liberal influence, you're talking about an entire universe and there is room for other views. I see no reason to brand an author as some have Carey unless that author is outright
offensive in either their works or their personal conduct. If you don't like the
New Earth series, or
The Moon is a Harsh Mistress, or works that don't happen to promote the values you like, it's fine not to like it, but I don't think people should act like it has no legitimate right to exist.