I'm not saying they will deny him a fair trial, I'm saying they could.
If they really wanted to extradite him to the US I'm sure they could. The ECHR and ECJ wouldn't necessarily do stuff all. They'd impose a fine and Sweden would probably just pay it with a back hander from the states.
You don't have to withdraw from the ECHR or the ECJ to break one of your promised obligations towards it. I don't go about saying "I'm going to withdraw myself from the UK legal system so that I can do what I want", I do it and take the consequences.Same for the UK, if we wanted to we could do likewise. So all that fluff about do I really think Sweden would repeal all its laws bla bla bla and enjoy all the political ramifications is a moot point. They get Assange, try him, fail as many expect, US meanwhile says can we have him please we've got a bone to pick, here we'll pay you too, they hand him over, ECJ and ECHR go oi what you doing. They go whoops, we're sorry, here's the money for the fine you'll impose on us. Whoopty do da.
My qualm isn't with his case in the Sweden, that's going to have to be public because of how high profile he is and so he will get a fair trial. It's what going to happen when they're finished with him. And I'm of the opinion that they will hand him over to the states regardless of what the ECJ and ECHR say.