looks like your friend didn't attend the court hearing, but he was banned by a court, so he has a criminal conviction for driving offences, and it may not have effected him getting ILR (did he declare this on his visa app?, may not have effected him getting ILR if he did),
but i'm not so sure when it comes to him applying for naturalisation, he could take the risk or have to wait until the conviction is spent ( that is 5 years after the date of conviction) and to not mention this conviction on his naturalisation app could be seen as deception.
Driving without a license is not a minor offence. The caseworker guidance makes it clear that its one of the offences that CANNOT be disregarded while considering an application for naturalisation.
in the guidance notes it says that the Home Office may choose to ignore "Minor traffic" offences for Naturalisation, in your friends case, its not minor at all.
so he can wait 5yrs and apply for naturalisation, or take the risk and tell them he has a conviction (which if they check, they can easily find out about from the police national computer) and maybe they will grant him citizenship, or if he doesn't declare it (and they check) he could be banned for deception
if your friend doesn't believe me tell him to phone ukba and check what I've said here is right..