I'm reading one of Voldemort's claims in this chapter to be that the resonance, rather than caused by Lily's sacrifice, was caused by Riddle's curse that he put on himself and his descendants [...]

That doesn't explain the Godric's Hollow explosion, since Harry wouldn't have been a Riddle instance at the time. I'm pretty sure Voldemort was telling the truth about the resonance, unless something else leveled the Godric's Hollow cottage and killed Voldy's last instance.

Voldemort can just shoot Harry now, however, where previously the curse would have prevented him from doing so.