You are comparing two different metrics. Government size on the one hand versus social stability on the other. That's an apples and oranges comparison.
While there may be an apparent correlation between the two in many cases, I do not think it is a true correlation.
A given society has to experience a significantly long period of stability, usually across multiple generations or perhaps even centuries, before such stability becomes part of their culture. Once it becomes part of the culture, perhaps government organization or size can change without destabilizing the society as a whole, but doing so before stability is part of the culture will almost as a rule destabilize the society. That is what you see happening in most unstable countries today: frequent changes in government, whether in the system, the group in power, etc. When the imposed power is removed, the society returns to the default level of stability (or instability as the case may be) to which it has evolved. Historically speaking, it is usually the case that powerful government (whether large or small in organizational structure) is the way that stability can at first be imposed over a larger geographical region, and the only practical method when there are instable neighbor states. Incidentally, this is why you cannot, for example, impose a given system of government arbitrarily on a given society without being prepared to enforce that system for generations if you want the society to remain stable.
In the world today we primarily see that the more stable countries have powerful governments. These augment their power through deep mutual economic integration with other countries, such integration usually having stability as a prerequisite.
However I think it would be naive to assume that there will be no further significant evolution in the organization of society and government systems or that any further evolution will be linear. Thus I doubt that there is any universally applicable answer to the debate between large and small scale governmental organization.