I agree that he should have lost at the voting booth, but the law is pretty clear on this subject.
The reason this looks sketchy in the first place is that it happened after they saw the election results, and one gets the feeling that if another candidate won they would not have annulled it.
Or elections is somehow different?
"Let them bring me prisoners, and I will find them law"
A lot of posters here have a very strange sense of "free speech" as well. The notion of free speech that the US was founded on was freedom from retribution from the government. That's it. It was not that you were free from consequences from fellow citizens that don't like your speech, nor does it imply that there cannot be laws requiring opportunity for political candidates to equally inform the public.
Ironically, the US will no longer have the original notion of free speech come January, and has long had a very broken democratic system where candidates have no notion of equal air time at all.
If they didn't caught it before election whatever happened is a fair game? You should read more on the topic, why this ruling was made. No dangerous precedent here. Honestly, this is the opposite.