> Your assumption here is that the enforcement of the new rule will be executed perfectly and without bias,

Not at all. Even if Reddit was completely biased and never enforced the rules against liberal-oriented cesspools, that wouldn't make T_D's current norms and behaviors any more acceptable.

The only problem is if you believe that Reddit will go far beyond their stated content rules and start punishing civilized discourse on the basis of political alignment. That would have a damaging chilling effect, but I think it's pretty clear Reddit has their hands full with rebellious mods and users who aren't even trying to stay within the posted rules and are making plenty of posts that really should be removed no matter where you fall on the spectrum of political beliefs.