Is not “shared values,” the main reason is that Navalny pushes the current USA narrative/propaganda of “Putin bad.” Not defending or saying Putin is a saint, sometimes, the best way to push Propaganda messaging is to use convient truths when applicable or when they align. This is not new, like at all. Russia, China, the UK, et al do it.
Assange does not push that narrative, quite the opposite that the USA Goverment can be highly hypocritical and that it can also commit war crimes and that it spies on its citizens, like what Snowden revealed, too. This is why the USA has tried to made Assange’s life a total living hell and the main stream media barely touches on it.
Remember when the NYT, among others sold lies from the Feds to push the war on Iraq? I 'member.