What is the basis of his "private life"? Is it having a British child? Or being the unmarried partner of a British citizen? Or being over certain age thresholds and living in the UK?
Also where is he traveling to? Is it his original country of residence or citizenship?
All of these factors can be taken into account when renewing private life visas. Also see
private life caseworker guidance.
Also keep in mind that the rules for naturalisation are much stricter and and not so forgiving about absences (and those rules are unrelated to the rules about private life absences). So he should reduce his absences from the UK at least five years before he is due to naturalise.
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.