He calls Alex a pathetic excuse of a son.
Makunga would often challenge Zuba to fights over the alpha lion position, but would be easily beaten. One of those fights led to Zuba being unaware of Alex being captured by poachers.
Makunga then used Alex, years later, to finally reach the rank of alpha lion. However, he is not a very good leader, saying the only solution to the fact that the local water hole was nearly dry was that they all would "Have to fight for it." This causes doubt about his role as alpha lion, and almost every animal on the reserve wants Zuba back. After the water was back, he tells Zuba and Alex that they were still banished.
Makunga eventually meets his downfall when being tricked into angering Nana, who was originally mad at Alex (and consequently treated him like she does Alex). However, the DVD commentary reveals that "Nana brought Makunga to New York in a kitty cage".
QuotesLook on the bright side Zuba after I defeat you and take over as Alpha Lion you’ll have more time to spend with your pothetic excuse of a son!