I don't approve of his persecution, but it should be clarified he's going to jail for calling them mentally ill freaks, etc. , not the skeleton stuff.
He uploaded
his legal papers on Twitter (currently X), so you can see what the police is focusing on.
In his offending post he said: "everything other (than man and woman) is a mental illness propped up by the curriculum" (Psychische Krankheit die durch den Lehrplan hochgezogen wurde)
When questioned by the police on this he clarifies that gender stuff is a paedophilic disease ("Das Gender Zeugs is eine Pädophilie Krankheit" ) and that the LGBTQI community are an extremist bunch ("extremistischer Haufen"). These are the legally relevant statements highlighted in the corrospondence, the skeleton stuff is tangential.