It's hard to know if he just has an animal instinct for or if he actually works out his rhetoric but this is an example of something Trump does which is quite clever - he hides an invalid premise/assumption behind a question that has a more reasonable answer. No, no-one has ever heard of being indicted for interfering with an election - but the false premise at work here which is implicit is that you've never heard of it because it has happened but no-one has been indicted, when of course the truth is you haven't heard of it not because someone shouldn't be indicted but because it simply never happened before. So the outrageous get glossed in what appears to be a reasonable compliant.
This technique is one way he is able to appear to normalize things which should never pass for normal.
And, really, I don't think it's any conscious intellectual effort. I imagine is just another reflection of his narcissism and the projection that entails. Since he projects all his behaviors on others, the idea that he is unique in trying to upset an election doesn't occur to him, thus it's normal and thus to him it appears he must be being singled out for prosecution.