为什么民运和反贼对界立建观感这么两极分化？

The assault provision of 18 U.S.C. § 351(e) divides assault into two categories: those that result in personal injury, which are punishable by 10 years of imprisonment and a fine; and all others, which are punishable by one year of imprisonment and a fine. The applicable fine is determined by the provisions of 18 U.S.C. § 3571. The legislative history of the section shows that the lower penalty was intended for situations in which a person strikes with his or her fist at a Member of Congress without landing the blow, or strikes only with an open hand and causes no lasting injury.

Absent a statutory definition of assault, the courts have looked to the common law and have concluded that an "assault" is:

An attempt with force or violence to do a corporal injury to another; may consist of any act tending to such corporal injury, accompanied with such circumstances as denotes at the time an intention, coupled with present ability, of using actual violence against the person.

美國官網https://www.justice.gov/archives/jm/criminal-resource-manual-1610-assault-18-usc-351e