Not wrong, because the case you linked does not conclude that what constitutes a threat (even in this legal sense) is what the recipient of the message believes.
It did conclude that it was a threat, and amongst the finer points of the case was that Elonis argued that the test should have been whether he intended the threats or not. The jury decided that a reasonable person would have perceived the accused comments were threatening.
Even a reading of a cursory summary of this case would have told you this. Did you actually read the outcome?
