The thing about genocide is that the concept was formalized as a crime, meaning you do actually have a burden of proof, and you do actually have to provide evidence, and requiring, examining, and weighing the evidence is no more offensive than requiring, examining, and weighing the evidence against someone accused of murder.
And you do actually have to do this analysis, because “genocide” is thrown around all over the place as a political tactic, and plenty of accusations are bullshit (or are you a genocide denier if you call bullshit on the accusation of white genocide in South Africa?).