Guys, going to trial does not equal a conviction. The police in this case have ample evidence to make an accusation, and an arrest. Note that at this stage, he is still being presumed innocent. In trial, the prosecution will have the burden of proving his intent to commit his crime beyond a reasonable doubt, which means that if there is but a possibility that he did not commit the crime of which he is accused, the jury must find him "not guilty". You can rattle on about there not being enough evidence. If that is the case, he will not be convicted, and, hopefully, will learn a lesson about what is and isn't ok to say anywhere, including the internet. Also note that bail is supposed to be high enough that it would be a significant loss if the bail were not repaid. That's the point of bail; you're letting the accused live at home until the trial, and so you require collateral so that they don't skip town in the interim. $50k bail is not excessive, and as long as he attends his trial, whether he be found guilty or not guilty, the money will be returned to him. So, the only thing he's lost is however much he needs to spend on a lawyer, which, as the defendant, he does not actually need to do. You see, he has the right to an attorney; if he doesn't want to hire one, the state MUST provide him with a public defender. So he's out of school from now until the trial day. Assuming he's not convicted, I'd say that the equivalent of a suspension from school is proper punishment for making violent threats. If he is convicted, it would be with the greatest burden of proof that our judicial system can require, and in that case, there would have to be proof beyond a reasonable doubt.
Also, threats of any kind are not protected speech, and people are prosecuted if their threats are dire enough. So this is hardly a violation of free speech.