I agree an opt out option would be best. Basically under each comment box a text that says:
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By posting here you are making your text available under the Creative Commons Attribution license. If you wish to not provide your text under the Attribution license please check here. To not see this message again check here. (you can change these settings in your profile at any time).
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By posting here you are making your text available under the Creative Commons Attribution license. If you wish to not provide your text under the Attribution license please check here. To not see this message again check here. (you can change these settings in your profile at any time).
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