Did he serve time on those charges?
Not a day. The FBI's evidence against the Weather Underground was tainted by revelations of unlawful agency actions and all charges were dropped.
One popular theory is that Weather Underground was itself a COINTELPRO agent provovateur group designed to tar the genuine anti-war Left with the "radical bomb-thrower" label. The Black Panthers, genuine leftist radicals, refused to have anything to do with either the Weather Underground or the C.I.A. cutout "Symbionese Liberation Army" poseurs.

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