It is safer to assume that he had specific and respectable reasons for becoming Eastern Orthodox, reasons that had to do with the differences between Evangelical faith and practice and Orthodox faith and practice. Likewise, it is safer to assume that he has specific reasons (perhaps not respectable ones) for his current shenanigans.
If he had been a Catholic, as I am, or Orthodox, I would not assume that his current apostasy was aimed at hurting someone's feelings. Likewise, Evangelicals ought not take it personally. People leave our respective Churches, each for his/her own reasons all the time. Many return. His father was certainly a remarkable man. Maybe he will return to the Evangelical Faith when his current problems are resolved.
Love Frankie Schaeffer in spite of his faults and pray that God will grant him the graces and that Frankie will accept them to serve God's plans for him, plans which have to be better than yours or mine.
Yes, love him - as Christ loved. But His love drove the money changers and pagans from the Temple in an overcoming zeal, whipping them mercilessly. Even this is love.