I didn't know that! That puts everything in a new light. I knew they were an autonomous state, but I figured it was the meaningless label it is in most 3rd world states. The article certainly suggests border control is by unauthorised thugs.
So is the pesh merga a component of a broader Iraqi civil service/police force, or is it just a component of the Kurdish authority?
The Peshmerga are indeed authorised by the Iraqi constitution to defend Kurdistan's borders. They are an official instrument of souvereign Iraqi and Kurdish government (albeit under purely Kurdish control). Note that the Shiites in the south have little sympathy for the Sunnis the Kurds are facing and usually vote to keep Kurdistan privileged.
They are absolutely not unauthorised thugs. They have uniforms, name tags, standard weaponry, and strict procedures. I was myself questioned by them at a border post for a few hours when I was there. (Questions were regarding why a European Jew would travel through Iraq without a passport or visa. They were completely professional even if a bit stunned after they stopped laughing.)
My guess is that the author of the article has never actually met those border patrols he is writing about. But that wouldn't stop him from describing them in a certain way. And that's my problem with the article.
It's usually more accurate to blame ignorance than malice in these cases, but the fact that the land is in dispute - rather than being explicitly autonomous territory - means the article is at least mostly correct. The Kurds don't have a right to control villages that fall under a different province. They should be pursuing their territorial claims in the courts, not with armed guards in the villages.
If the land is in dispute the (Arab) governor's actions (calling his armed guards) constitute the same kind of behaviour. However, the Kurds have a better track record in anforcing just law. The governor's base (Mosul) is famous for Arab militias hunting down (Assyrian) Christians. The Kurdish base (Arbil) is famous for being terror-free and having a working Christian quarter. (And from my own experiences I can also confirm that there is no anti-Semitism in Arbil that I could detect.)
Even if the Kurds are not souvereign over the disputed area, it would still fall under an umbrella of "Kurdish occupation", which means that enforcing border controls is still not the same as random thuggery.
And if the Kurds pursued their claims in the courts rather than in the villages, the area would be Christian-free within a year (and the Kurds would lose any local elections about whether Mosul should be part of Kurdistan).
When I spoke to Kurds in Arbil the only common complaint about the Christians was that they don't speak "Christian" any more. By "Christian" they mean Aramaic. The Kurds, from all I have heard, love multikulturalism (under Kurdish control) and were very proud of hosting Christian populations. The Christians (Assyrians) are the original native population of northern Iraq before the Arabs or even the Kurds took over.
(Incidentally, I don't know if the elections the Arab governor won took into account the fact that the Assyrians, i.e. the native population, was fleeing towards the mountains at the time. I'd rather see the Kurds rule over the Assyrians than the Arabs. I have heard horror tales from Assyrians about the Kurds as well, but it never approached what I heard from Assyrians about the Arabs.)