Yep. Pay to poll on a private users feed which is not monetizing free speech but a rough fix to a bot spam problem is no different than you paying your isp to post the above reply. Paying for a voluntary opt in service is ok it is not an attack on peoples speech or freedom further there would also be nothing stopping you from setting a poll at a zero fee rate. Lastly if you are zapped for a good comment, thought or critique would you be monetizing speech or accepting value for value again voluntarily.