I mean I majored in biology and took a class on animal behavior and "satellite males" are common enough among reptile, insect, and bird species.
Commonly they are named "satellite males" because they will skirt and orbit like a satellite around another male's territory and attempt to mate with any females coming in. Others will try to jump in and mate with a female while the main territorial male is distracted or in the middle of copulation. There is also a subset of satellite males that will mimic females (aka look morphologically female) to gain the protection of the territorial male and mate with his harem when he isn't looking.
Basically it is a very passive method of breeding, as these males mate opportunistically and don't work on gaining territory and resources to court a female. The reason satellite males exist is because it is a relatively effective method of passing on your genes.
Basically she's saying he's passive, and gains female attention by being around his more popular brother. Rather than calling him pathetic, I think she's just pointing out that he has benefitted from his brother's resources and isn't working towards being likeable.
That's my biologist's 2 cents though.