I really do not see why this isn't Canon.
Alucard Has Organized a Church, Fired off Countless Holy Crosses, Day-walked, and maintained his humanity.
Plus his Father isn't a Legitimate Vampire, Gaining all his initial Power and Vampirism from the Crimson Stone.
Being 1/2 Alucard and 1/2 Belmont in Trevor would Explain Simon's Ungodly Strength and Juste's Glow and Vampire Trail.
Canoning this game makes everything fall in place a bit, and IGA could always change details like he did with Bloodlines.