You are right, but that still does not apply to this situation. While decentralisation of populism would take power away from centralised influencers, Soros is not arguing against this decentralisation. Quite the opposite.
The internet has new forms of influencing power that the previous media did not have. What he warns against is the centralisation of those powers in the hands of a few players, and the possibility of these players working together with totalitarian governments to create a dystopian surveillance state (personally, what I am even more freaked out about is the idea of a decentralised totalitarian surveillance state - there was a recent Wired article on how China is experimenting with this).
The claim that Soros has a "strong states are fascist"-rhetoric does not make much sense either. This is what he actually says in the article:
> “The internet monopolies have neither the will nor the inclination to protect society against the consequences of their actions. That turns them into a menace and it falls to the regulatory authorities to protect society against them,”
There are no business incentives for Facebook and Google to clean up their act, so he explicitly calls for more regulation. How is that not asking for a strong government? Of course, that's not what GP meant with "strong states". His "strong states are fascist" claim is that weird kind of self-denial that you typically see with people defending fascist governmental actions, but not wanting to be called fascist.
It typically plays out like this: person A argues that "government X is fascist, because A, B and C", where A, B and C are typically human rights violations carried out by X. Then person B, who is pro-X, reasons "But A, B and C are ways for our state to be strong! X is not fascist, you are just against strong states!" No, person A isn't against strong states. Person B just has ridiculous definitions of what a strong state is. The governments of the Nordic countries enforce a ton of regulation on companies within it. I would consider that a strong government. Few would call it fascist. Person B would probably call it weak.