"vir-" is a preëxisting masculating prefix. I would read patrulo as "A fatherly person", rather than a parent, as "-ul-" turns an adjective into a person embodying that adjective.

(ge- is the neuterizing prefix, but in my extremely limited dabbling, it's mostly seen in plurals: gepatroj for parents, but for a single parent, one generally says patro for father and patrino for mother.)