Given that the US has filled no charges against him, made no extradition requests to Sweden or the UK, and that there seems to be a fair degree of legal consensus that the European Court of Human Rights would deny extradition for the sort of charges that the US could plausibly file against him it seems to me that to believe that Assange has credible reasons to try and avoid obeying the request that he attend questioning in Sweden for what would be considered fairly serious accusations in most western countries is to buy into a conspiracy theory.