That's a matter of perspective. If someone is critiquing you and you don't like it, you can easily twist that to say you were attacked and effectively shut down conversations you don't agree with.
Cyberattack is a fairly generic term (as is anything "cyber-"). Just intentionally joining a Zoom room you're not supposed to be in/know about is probably "unauthorized access to a resource" and thus a "cyberattack" according to some definitions, and mainstream media, school administrators, ... are going to use those kind of definitions.
E.g. random definition pulled from merriam webster dictionary:
> an attempt to gain illegal access to a computer or computer system for the purpose of causing damage or harm
One can argue that there's not enough focus on the attack on a system here, but I'm not surprised it's used that way.