If the government wins costs will most likely be awarded - to Harry.
However Harry is a private individual, not a senior, working member of the royal family. None of the other members of the royal family get tax payer funded security, nor do they pay the police to protect them because the police are not for sale. Only working, senior royals (the Queen, Prince Charles and Camilla, Prince William and family) get full time, tax payer funded security. Edward and his wife and Princess Anne get security only when engaged in royal engagements. No other royals get tax payer funded protection. Should he be able to buy it? No! The police are not for sale. Large gatherings such as football matches pay a reasonable share towards the costs of policing matches/events, but otherwise no one pays for police security. Harry can pay for his own security in the country, absolutely no problem, but it cannot be the tax payer funded police. They are not for sale!