The theory's basically got it assbackwards. Any army powerful enough, and thus dangerous enough, to lead a country into a war dangerous enough to seriously endanger it will also have made its power, and its willingness to slaughter its country's citizens, felt in other ways before that. That's why democracies don't go to war against their neighbors.
That's all true, and well and good, but here is my question for you:
In the case of 'democratic' aggressors, such as for example the United States, does your analysis imply that they only attack when the victim is weak enough that the conflict would not constitute 'a war dangerous enough to seriously endanger it', or are we to understand that you consider such ostensible democracies as largely controlled by their military?
I consider both to be very reasonable positions, and of course there is enormous gray area available in between.. just curious where you stand.