They may be trumped up. They may not be. We (random people on the internets) certainly don't have enough information to say one way or the other. They are certainly serious, though.
What we have are courts to hear the evidence and come to a conclusion. Largely open courts, whose decisions can be scrutinised by the press and public.
Mr Assange is attempting to avoid the confrontation with the courts. He believes he is in danger of either a miscarriage of justice or extradition to the US. These things may be true, but the world will be watching carefully.
Anyway, this is something of a digression from the topic of the article, but your automatic assumption that the women involved must be lying simply because his arrest is convenient for various governments certainly won't endear you to other readers. And you are somewhat undermining your earlier argument about how the police are the right people to deal with issues at conferences given how little faith you apparently have in European legal systems.