As it has already been established that disabling others from seeing the source isn’t possible (without actually hacking each of your visitor’s computers! :eek2:), perhaps you can try some kind of counter-intelligence.
For instance, maybe putting stuff in your code that is meaningless to SEO but under the guise that it is there for SEO just to throw off anyone you’re worried about… but on the other hand, this in of itself may prove counter-productive for SEO 
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trying to block right clicks will just annoy them at best, even firefox has a simple tools->webdev->page source option. If you want to further annoy them you can encode your source like google does though, but that again won’t stop the determined users.