attorney.
I don't think it will actually impact this case, but a cop shouldn't leave any room for violations of rights like that. In that situation his attorney would likely have said " Invoke the 5th, don't answer ANY questions, comply with any lawful orders and I'll meet you at the police station."
Unless the cop way trying to trick him into confessing and speaking against himself, there is no reason for him to discourage calling the lawyer.
Hopefully it doesn't hurt the case, but it potentially could and there is no reason for it.