Why is Borros Baratheon green?

Something that doesn’t entirely make sense to me is why Borros Baratheon sided with the Greens. I understand that sexism likely played a major role, but Rhaenys—one of the leading figures on Team Black—is literally half Baratheon. By extension, if Rhaenyra won, Jace’s children with Baela would carry Baratheon blood, meaning House Baratheon would have a direct connection to the throne.

Yet despite this, Borros chose the Greens, who only offered his daughter to Aemond—a prince who was third in line to the throne at the time (behind Aegon, Jaehaerys, and Jaehaera). Why would he support a faction with a weaker tie to his house rather than the one that could potentially place Baratheon blood on the Iron Throne?

additionally, why did Rhaenyra send Luke to Storms end instead of Rhaenys who had a direct tie to Borros and could convince him better then luke could?