People are freaking out, quarantines keep them calm, so we go with quarantines.
I recall another period in US history where we took innocent people and locked them up out of fear... We don't look on back on that with pride. The AIDs quarantine proposed in 1980's in California didn't fly. We didn't quarantine symptomatic people with swine flu. We don't quarantine active carriers of HIV. Trying to quarantine non-contagious people just to make you feel warm and fuzzy is wrong.