Bit of a gulf of a divide between the two, ethically.

in one case: Someone actively put themselves in a situation that had a high likelyhood of becoming violent, and did so for political reasons (I think the case could be made that the protesters were also at fault for engaging with Rittenhouse in a threatening manner)

In the other case: Someone minding their own business in their car was violently attacked, and proceeded to knowingly or unknowingly kidnap a family member which could result in life-changing horrific scenarios if not dealt with immediately.

The Rittenhouse case isn't super justifiable, simply because he really set himself up for that scenario to occur.