it was an act of whistleblowing
Also not true.
Whistleblowing is for workers, and applies in very specific scenarios that don’t apply here at all.
The student no bout had a grievance, and would have been quite justified in making a compliant to the school leadership, but he is not a whistleblower.
www.gov.uk/whistleblowing
Does the usual insistence on facts, evidence and sources not apply when it suits your position?
Again, there would need to have been very clear grounds for exclusion, and there’s is a rigorous appeals process. Posting the video might well have formed part of the grounds.
Saying stuff in class that goes against a school policy is not grounds for exclusion, and you’re being really misleading and manipulative by insisting that’s what happened.
Imagine how many kids would be out of education if schools could exclude for saying something in class. Every homophobic remark, every bit of casual racism... it doesn’t work like that, as any parent knows whose kid has been on the receiving end of verbal abuse in class.