I see the school officials side of this. This speech does tend to impede on the educational process. However, if we allow schools to suppress students, even at a distance (and off of school machines), this is not a slippery slope, it is an outright violation of our citizens’ first amendment rights.
I think of this as I think of all laws. People reach, stretch, and expand the purview of the law (or it’s exceptions) until it ceases to resemble the original intent. I believe in the exception regarding the disruption of the educational process. However, this doesn’t mean that we should be using it as a group control mechanism. This shouldn’t be something that we hold over students saying if we don’t like what you say (no matter where you say it) you will be punished.
Schools are soon to be subverted in ways that we haven’t seen in over a hundred years. If we allow non-educational spaces to be used for suppressing free speech, learners in any educational setting won’t be safe to speak freely anywhere, anytime.