In the case you refered to they wanted to arrest the defendant in absentia, which the courts declined. In Assange's case the court has ruled that he should be arrested in absentia. Probably because they are harder on sex crimes (the state feminism of Sweden is quite draconian when it comes to sex crimes).
Furthermore, in the summary of the case you refered to the court says;
"Med hänsyn till gärningarnas omfattning och karaktär får det anses befogat att L.O.K. är personligen närvarande vid det förhör som nu skall hållas. "
Which means that they think it is justifiable that the defendant should appear in person for questioning. In other words, the same finding as in the Assange case. So this case doesn't support your arguments at all! (Perhaps this was changed on appeal or something, but nothing indicates that this should have been the case in the finding you linked to!)
Also, in the case of Assange, we are talking about a sex crime. There might be other reasons for wanting to have him come in for questioning, such as making a request for DNA samples or something. I haven't actually heard that this should be the case, but it is not unreasonable considering the allegations against him.
I think that Sweden's sex crime laws are draconian an contraproductive. But, in accordance with the law we have today, the treatment of Assange is quite correct. Whether or not they are reasonable is another matter, but they are following the law such as it is. Believing that this is a honey trap with the purpose of extradating Assange is just silly. Sweden's sex laws are very hard and if you are in Sweden you have to obey them and ignorance is no excuse for breaking the law.