No. In and of itself an online threat is not a "clear and present" threat.
SF, a "clear and present" threat requires someone who's making the threat actually be 'present' which would mean they've taken at least some steps to carry out the threat. Especially if they made the threat online and proximal to the threat they are now present at the target of the threat. So, being "present" is a step toward getting arrested versus merely making an online threat.
In order for it to be "clear" there has to be at least some ability to follow through with the threat. Ex: I point a glock 9mm at you and say 'im going to kill you mother fucker!" Versus I point an obviously fake plastic gun that shoots soap bubbles. If Im armed with a water gun, shooting soap bubbles, I clearly don't have the ability to carry out the threat.
All of the parameters you put out does not have to be met by Florida statute:
There are separate statutes that cover school shooting threats and bomb scares. Florida Statute 836.10, prohibits anyone from making “written or electronic threats to kill, do bodily injury, or conduct a mass shooting or an act of terrorism.”
Florida law does not state any of the stuff you included such as planned steps, detailed towards a specific person and lead to negative action.
That’s it. So if a student in Florida says “I’m going to shoot XXX middle school up,” yes, they can be charged and convicted.
Some student in Virginia made a bomb threat toward his school and he was arrested and charged.