If I owned 1% of all gold in the world, and was online singing the praises of gold, would that be against the law? If I owned 1% of all Romanian currency, and I was singing what an economic resurgence that Romania was about to have - would I be in violation of any law?
Not at all. To be frank, talking up an asset you own is so common that it even has a term: "talking your book." Even in the thoroughly regulated asset markets, all you have to do is disclose honestly how much you own.
There are special rules for "insiders," but those folks are specified by the relevant laws. There are also special disclosure requirements for stocks if you own a large fraction of an issue. The précised percentage varies - 5%, 10% 20% - but the gist of the special disclosure consists of letting the securities regulators know you have them and (in a general sense) why you bought them.
This significant-ownership disclosure requirement, however, has a special purpose: it's to foil stealthy takeovers. And that intent puts forth an obvious question: does a 'takeover', in the sense of holding 50% + 1 of a cryptocurrency, have any meaning? For a listed corporation, 50% + 1 gives you control of the thing - which opens up the possibility of abusing that control by pulling shenanigans that benefit the majority owner but not the minority owners. How does that apply to a cryptocurrency? The closest similarity, for PoW coins, is controlling 51% of the hashrate. It is not owning 51% of the cryptocurrency itself.
A cryptocurrency is not a corporation. That plain fact means that there's a lot of good reason to object to a simple law that brings cryptocurrencies as if they were equities or debt securities. This fact alone all-but guarantees - if the new crypto mavens get into lobbying like the tech giants already have - that: a) cryptocurrency will likely have a new regulatory agency; b) it will take a long time for the details of the enabling legislation to be hammered out.