Does mbovu in this context convey the same meaning as rotten in the English sentence?
I think in this context it should mean "bad" and not "rotten"
Yes, then I've understood it correctly. When you say "rotten" about a person, it would usually mean a really, really bad person. If you use the word for a profession, or someone holding a position, it would usually mean that the person is really bad at doing what he is doing.
In kiswahili the adjective mbovu is rarely used with a person. Although it can be correctly used to mean bad. The most common and more acceptable is mbaya.. Mwalimu mbaya - bad teacher. Mtoto mbaya - bad child
I get the feeling that maybe evil is a better translation? At least the places I've encountered mbovu and waovu are in a more philosophical or religious context, and then evil would be better, as in not being bad at doing something but being in general a bad person.