Security through obscurity is a very valid way to secure something. It shouldn’t be the only way of securing something, but it can be a valid additional layer.

The knock sequence is a secret, just like a password. It may not be a particularly strong secret, but is is strong enough to keep out casual attackers. You’ll still need additional security, but sshd is well equipped to provide that.

I’m not confident it is a Russian op, but Russia has always fueled both sides of the political spectrum. They don’t necessarily want one side to prevail, they just want their opponents to be divided.