Does the British government banning or allowing the IRA flag legitimise or delegitimise their presence in Northern Ireland? What about Spain and the Basque flag

Does the British government banning or allowing the IRA flag legitimise or delegitimise their presence in Northern Ireland? What about Spain and the Basque flag? I would contend that the fact you feel you need to ban it, legitimises it. Plus Taiwan's government is democratically elected, so if you go down the path of illegitimate governments, Chinas ruling party isn't looking so great there either. I agree though, that probably is what they're trying to do. It just comes across as petty and pointless.