Praising a murderer for committing a murder is not incitement and is protected speech. Under Brandenburg v. Ohio (1969), speech loses protection only if it is directed at inciting or producing imminent lawless action and is likely to produce it. A comment on a murder after the fact can’t meet this standard unless the comment is “go do another murder right now!”
Kimmel also did not praise the murderer. He implied (incorrectly as it turns out) that the killer was right-wing.
Your misstatements of the well-known facts and law in this case cast doubt on the effort you put into researching the other issues mentioned.
He did more than imply the falsehood. He implied that people had no good reason to disbelieve the falsehood, and that the right wing was seeking to deceive on this basis for political gain. In doing so, he (perhaps inadvertently) ran cover for the ideology that was actually responsible.
Right-wingers have lost their jobs in the US many times for far less, even when their comments were on social media accounts unrelated to the job. When these responses are described as unjust or disproportionate, American left-wingers have consistently and repeatedly (across a span of many years) told me the same line about how 1A only applies to government and not corporations. Which is correct, but also entirely missing the point about bias.