Not always,in my opinion. Sometimes people are forced into punishment far worse than their illegal acts. They could be held against law even though it wasn't them sometimes. Really depends where, when, who, and what. If murder or any drug related acts happen that was on purpose, then it's fair to punish the inmate.
There is not a specific antonym for diaspora, but the opposite of a diaspora would be the regrouping of a community or the coming together of a community. It could also be a renewal of a specific cultural group or ethnicity coming back together in a sort of revival of their culture.
He was a commodore in the United States Navy who, in 1846, claimed California for the United States.
Hiram Johnson managed to get the California Proposition 4 passed which was a constitution amendment to the constitution of California which gave Women the power to vote. This was in 1911, years before the 19th amendment was passed on a national level and before women from all around the United States of America got general suffrage rights.