Calvinism is just a historical label that has come to represent a particular soteriological view. It doesn't mean all "Calvinists" support or believe everything Calvin taught or did. Same is true of Arminianism.
I believe the OP is much ado about nothing. Culture has changed and things like slavery and Heretic executions were supported by otherwise decent followers of Christ. Calvin was a genius and notable biblical scholar. His work on prayer is amazing. I disagree with him on a few doctrinal points, as did Arminius, but in the great scheme of things we are very close and all of us would do well to show him the respect he deserves while still being able to rationally and objectively disagree with him on particular aspects of his teachings.
Just my two cents worth...
So, Calvin was just a nice guy who executed people or threw them into prison because they disagreed with him. I guess that would make Hitler, Stalin, and Mao Tse Tung all nice guys simply because widespread killing was the norm at the time.
Sorry Skan, can't agree with you here.