I understand you have strong and sincere feelings about the parent posting, but I feel it's unfair to frame the poster's comments as construing his wanting to be judge and jury on what constitutes patriotic dissent.
People who deliberately spread unprove-able smear campaigns saying, like GWBush ditched his military service with the air national guard, or that Obama wasn't born a citizen on US soil are being irresponsible hate mongers, in my opinion. Is their speech protected? Absolutelty. Is is promoting responsible public discourse? No. Is it "patriotic?" *I* don't think so (although supporting their constitutional right to say it IS).
SCOTUS has a series of rulings on what is considered to be protected speech and I wont debate that here (I agree with most of what they say, not that my opinion makes a whole lot of difference there).
I'm fairly sure the GP has a problem with anything he considers to be "misinformed fear-mongering, blatantly FUD-spreading speculation, and purposeful yet meaningless obstruction..." and so do I. I'm also sure you can cite numerous examples of lies and misinformation about those on the right (like tea partiers, for example) and you would not consider this to be "patriotic."
I'm willing to be he considered the following to be "patriotic" dissent:
1) non-violent Vietnam protests
2) non-violent Civil rights protests (many were violent because police simply beat/water hosed, or - in the case of Kent State, SHOT the protesters)
3) loudly proclaiming, via social media, opposition to lies about public figures on the left or right and/or the causes they support.
The problem, as you allude to, lies in what would ultimately follow from trying to regulate speech on it's ethical merits (or lack thereof)
As I see it, your argument is a red herring, because the GP never suggested this. I believe he was talking about passing his own personal judgment on what *he* thinks is *patriotic* dissent and how people should engage in rational, civil discourse on matters they disagree with. You may not agree with his doing this, but he still has the right to do it. I support his right to do this.
And I support your right to strongly and loudly disagree with him.