Its not reasonable, and certainly not humane what happened on Tienanmen. But it is understandable. Those government cadres feared the return of the red brigade- they had seen what happened with 'elite' that fall from grace during the rule of the mob by Mao. If a democratic uprising would show the same behavior tendencies as the red brigades, a - its either us or them - mindset would have governed most decisions.
How did the students talk and negotiate with the CCP on Tienanmen?