No, it doesn't set a precedent. I don't even know if people who are saying that know what the word "precedent" means.
If the verdict is sending a dangerous message, it's because or the lies of the media; not because of the verdict itself.
The "precedent" thing should be obvious. Jury verdicts don't change law. OJ being found not guilty didn't make murder legal.
Even if you could conjure up some mental gymnastics to argue that the verdict in this case will influence future, similar cases; well, first of all, the laws are different in each state. If a man in Florida shot and killed somebody in self-defense and the Stand Your Ground law were relevant, even if he were found not guilty in Florida the same action in Massachusetts would result in a guilty verdict because Massachusetts is a state with a duty to retreat.
Still, verdicts don't set precedent. Any person getting off of criminal charges is acquitted because that specific group of twelve people were unconvinced of guilt beyond a reasonable doubt. A different group of twelve might find differently. A different case may have more evidence available.
As for the message that this supposedly sends that white people can show up to a BLM riot with a gun, wave the gun around, provoke people, and shoot anybody who he provokes - well, if anybody gets that message, it's because of the people who have been lying about the case.
After the prosecution's first story fell apart they tried to get Rittenhouse on provocation. They had two instants in which they claimed that Rittenhouse pointed a gun at somebody. One is an unidentified man in yellow pants who was on video yelling at Rittenhouse that he pointed his rifle at him earlier in the evening - there's no other evidence. The other claim was that Rittenhouse pointed his gun at Joshua Ziminski and provoked the attack by Rosenbaum. Again, there's no good evidence and we know that Ziminski was brandishing his gun all night before the altercation.
If the evidence ever showed Rittenhouse running around pointing his gun at random people and threatening them, Rittenhouse would be awaiting sentencing for murder convictions right now. Only, there's no evidence of that. If anybody is under the impression that they can kill people that they've threatened and provoked with a deadly weapon and get off by simply claiming self-defense, it's because of the lies, not the verdict.
If there is a message here, it's that if you're innocent you still have a shot at being exonerated even if half the country is lying about you.