Earlier quoted context omitted.
To my understanding, the judge found that Assange's rights will be sufficiently upheld by the US courts, based on the US constitution and precedent - so, she is willing to allow the US judicial system to conduct their trial (if it weren't for the abhorrent conditions in which he would be kept, which she found too likely to be detrimental to his well being). It is not really a matter for an extradition judge to rule o…
Don’t the charges at least need to be credible?
Of course, they do have to be charges for something which would be illegal in some way in the UK as well. If the US criminalized ice cream consumption, you would not be able to extradite someone in the UK for having consumed ice cream in the USA, of course. But this is not the same as, say, extraditing someone accused of murder in the USA who is not known to have been physically there - the extradition judge may be ok in not looking at the evidence that the charges are based on (except maybe to ascertain whether they may be a sign of a politically-motivated trial).