(rar, warning, hardcore opinion!) Someone who has to build THROUGH people is ultimately hollow and meaningless. ^^; An extrovert should only build OFF of people, to which the extrovert forms oneself socially yet ultimately will still structure their development by internal thinking. An introvert has a similiar danger which is to -avoid- making a worldly impact, which isolates the individual into futility.
One must remember that humans always partake partly off of both ends...It is unhealthy and debatably impossible to be raw intro/extro, and it feels like your brother is asking for a raw extro experience ;.;
(edit: added))
I say this because it feels like the basis of a proper decision is that one has to have friends and be social, even as soon as immediately. >.< proper extroversion comes out of a pace, rather than being dictated by fullfilling a standard.