Identifying pro-Putin shills is not what's being done here. This is just accusing people that don't agree with everything said about Russia and the depiction in the US media of the current conflict in Ukraine of being Russian shills.
I remember when people who questioned the Iraq war had to constantly defend themselves from accusations of being terrorist shills. This has the exact same chilling effect.
edit: I am honestly interested in evidence of shill posting. I enjoy the detective work. If your evidence of shilling is that you think that the opinions people hold could only be held by shills, you're just stifling dissent in the traditional way that it has always been done. It's no more noble or complex than that.