I sincerely doubt the Koran or hadiths say any such thing. That may indeed be a common dynamic, but that's very different from it being official written Islamic doctrine.
This is especially so because until recently Islam did not expand by immigrants leaving Islamic countries and moving to secular/Christian countries. Islam expanded by conquest, making the 10% meaningless.
I wonder if I’d be able to find that source, to see what was cited.
If the principle of abrogation is specifically stated in the Quran or hadiths then Muslims would be combatants regardless of the percentage issue, since Mohammed’s later, violent commands would replace any of his earlier, more peaceful quotes that people use when claiming that Islam is a “religion of peace”.
It would be interesting to ask Muslims why they don’t routinely kill non-Muslims in America and other places, as commanded in the Quran. It would be interesting to ask them why they haven’t executed Obama as an apostate yet, as commanded in the Quran. For them to have an official excuse, there must be something written about when that command is required and when it is simply a goal to strive for.