Disclaimer: I'm not a history major. I've just glanced over the references that the author provided, as well as do some cursory Googling. I could be completely wrong.
Somerset v Stewart outlawed chattel slavery in England in 1772, but the rest of the British Empire was unaffected. Therefore, colonial America would have been unaffected until 1833, when the Slavery Abolition Act was passed. I don't think that using the case in England to say that slavery would've been abolished in colonial America, had we not seceded, is a fair or truthful claim.
Britain was fond of using the concept of terra nullius to lay claim to lands, most notably in Australia, New Zealand, and Canada. Britain also killed quite a few natives on their own. The only reasons that you see less atrocities committed by Britain in Canada/Australia is due to there being less people and Britain didn't have as much of a desire or reason to have an expansion explosion like the original thirteen colonies. The author claims that yes, Britain would have eventually expanded west in North America, but there would have been less deaths. That's 100% opinion and has no basis in fact. Furthermore, while mentioning the Mexican-American war and some vague note of how Mexicans "were no angels," he conveniently leaves out the fact that the Mexican government put a price on the scalps of Apache men, women, and children.
As for the government side of things, I really don't know enough about how all of that works to really agree with or refute his points. I don't particularly enjoy the current government. It seems to move slowly and then backwards. Things go in circles for years, it seems, and nothing gets done. However, I don't necessarily think that the ability of the government to "decide it want[s] a carbon tax" and then it become a reality is a good thing either. One could argue that the carbon tax is a good thing. I'm not going to get into that one way or the other, but the ability of the government to get exactly what it wants is not a good thing. When speaking about the ease of passing laws, you have to consider both the laws that you would support and those that you wouldn't. Again, the author only presents a single side to the argument.
Thanks for linking the article. It definitely provoked some thought!