The fun answer is "Yes - it certainly looks like it."
The strict legal position is not clear to me at this time.
We don't know if the issue of defining "idiocy" ("tosse" or similar IIRC.) was considered by the court.
The variations on the theme are too many to speculate - so one example will have to suffice until we see the transcript. (If ever.

)
The argument could be that:
1) "idiots" was shown to be accepted by the relevant community as applying to 9/11 Conspiracy adherents; AND
2) that Harrit had by his own action aligned with those conspiracy adherents who are regarded as "idiots" by the relevant community; AND
3) that any damage to his reputation was caused by his own alignment with those who are known to be regarded as "idiots".
If those were the steps then the courts consideration of the facts would stop at that point. Harrit loses on basis of 1, 2 and 3. Particularly "3".
So the question of whether Harrit qualifies as an "idiot" would not even be looked at by the court. The issue remains moot.
In that event what could be said to be legally accepted was that he aligned with a class of persons who are commonly regarded as idiots. That does not make him an idiot nor does it imply that the court ruled that he was an idiot. (BTW nor does the court rule whether the conspiracy adherents are
in fact idiots.)
There are multiple legal possibilities and speculation before we see the transcript could be way off the track.
(And every use of "idiot" or "idiocy" in this statement needs to be read as reference to the actual Danish word - "tosse" and derivatives as far as I amaware.)