Merits may affect shitposters aiming at higher ranks. It's still not a free speech issue in any conceivable way. They can still post their shit. If we follow your fallacy we should just close the forum because any rules can be twisted this way.
You contradict yourself. If merits affect what you deem 'shitposting' they are affecting free speech. Besides that you are totally missing my point. I am not against restricting certain modes of posting but against the abuse of the systems that are installed. I am against the installing of special merit and trust powers at the subjectivity of a privilaged few members with lack of ethical disposition, who thus abuse those powers.
There is no contradiction. "Affect" is not the same as "prevent". Shitposters can still shitpost. I suspect some won't when they lose the financial incentive to do so. Not being paid for free speech is not the same as losing the right to free speech. To use your own example, if you stand in Times Square and yell "Trump is a cunt" you shouldn't expect to get paid for it.
You keep talking about abuse but you are failing to provide any proof of how this hypothetical abuse can prevent you from speaking out within the rules of the forum.
For example, you can still insinuate that I get paid for my signature and there is fuck all that merits can do about it.
Yes, I can insinuate that and it will not affect your forum possibilities because I have no super merit or trust power. But if one of the privileged members insignuates things about me it can, and often does, have consequences for my forum possibilities, even if the insinuations are not true.
There you go, free speech problem solved, you can keep shitposting. Let's tackle world peace next.