Paternity leave and furlough

Employee of more than 20 years was furloughed and just asked by his employer to return to work.  He initially refused as he has concerns about his wife’s health but has now gone back.

His employer have told him he should have taken the leave whilst on furlough and he cannot now have paternity leave as he returned 8 weeks and one day after the baby was born.

Can’t see anything to say the rules on claiming paternity leave have changed in line with Covid but hoping we have some argument