I do not rule out that someone is trying to greatly reduce the value of this portfolio of altcoins in order to be able to buy them at a bargain price in anticipation of the impending bull run. The big cryptocurrencies are not affected simply because big capitals are already involved in these assets and such accusations could not badly shake their ecosystem and therefore their price. So they are neatly bypassed, although they could also make the list, especially BNB and DOGE.
Well, I think it's rational to short cryptos which may have a smaller market due to their categorization as security. I don't really believe they will recover that much. And there were some of the "big" cryptos in the list, such as Cardano.
Regarding "the next coins to be classified as securities", I agree with BNB being a candidate (wasn't it already categorized as a security recently?), but DOGE is decentralized and has no central authorities, neither does it use Proof of Stake or other mechanisms which could be interpreted as "common enterprise", so I believe it's not "in danger". I would not be so sure about ETH, and about almost all coins except
these (with DASH as an edge case which already has been accused to be one).
Personally I just think it's part of the 4 year cycle that occurs, the inner workings of it as it were.
All of this makes sense, unless we witness market cycles break down and stop working. Personally, I don't give much credence to all this crushing on cyclicality, because it could all break down at any moment and cycles, or market trends, could stretch out, over much longer periods, like 5 or 7 years. It would be too easy to hope that everything would repeat all the time every 4 years.
Here I agree with Xal0lex. We have to take into account that there were, until now, only two cycles of about 4 years (2013-17 and 2017-21), the previous cycle had only 2 years, and the 2017-21 cycle is debatable due to the low in 2020 and the 2019 high (in some graphs, it's shown as two cycles: 2017-19 and 2019-21).
However I don't see really the connection to the SEC "securities" debate. That's clearly a move independent from market cycles, triggered by a identifiable event (or a group of events, as there are various lawsuits and SEC statements involved which have driven the value of those coins down).