My stepfather was hit from behind by another car police report shows only 2 cars involved- his and buck who hit him but buck claimed phantom law

Police report showed that another car was not involved and both cars are insured by the same insurance co but insurance co is making my step-dad pay his deductible 500 for getting rear-ended and it was not his fault to pay for the repairs and they would cover the rest. Should he hire a Lawyer? He does not have a lot of money so thought I would turn to the internet to help out. It has also been 6 wks and they just told him all this today that he would have to pay and the other guy was protected under phantom law but police report states there was not a 3rd vehicle. Please let me know