The argument is that in general a professional military serviceman is worth quite a number of his domestic insurgent counterparts, the problem is that domestic insurgents have a lot more staying power than a foreign occupational force without significant support from regional allies. Due to the size of America and who our regional neighbors are any occupational force that is actually interested in pacification rather than decimation is doomed to failure. That is literally the least important thing in the hypothetical scenario of a foreign occupation of the US against American domestic insurgents. Small arms are going to be near useless for the same reason they don't "guard our freedoms from the tyranny of government" that you cranks are almost always on about, more important to the insurgency are National Guard and Reserve armories with 155mm shells and honest to god mines. The last thing an insurgency should be doing is trying to engage the occupational forces in a firefight since it inevitably leads to a fire mission or an airstrike killing all of them.