Trump's claim isn't quite that tenuous. Check section (2):
there is a rebellion or danger of a rebellion against the authority of the Government of the United States
That's the basis for this. They're characterising Angelinos resisting ICE as "a rebellion against the authority of the Government of the United States", since ICE is an extension of that same authority. It's a weak claim, but not as completely buckwild as claiming a foreign invasion.