If I were you and I had posted anti-Putin content online, I would not risk being detained (or worse) if I were to go to Russia. Chances are Putin’s government is not keeping a list of any and all individuals who have expressed anti-Putin sentiment online.
However, the Russians do have very sophisticated technology if they can hack into other country’s election systems in order to influence the outcomes in their favor. And, Putin has been known to arrest protestors all across Russia. He has also been known to have journalists and protesters mysteriously killed for speaking and writing negatively about him. So, why risk it?