No, I don't think, at that point in Peter's spiritual trek, that he would go about deliberately going against God in any circumstances. I just construe it that in that sentence, he was not talking about a 100% and only CAPACITY on that score. I believe he was saying something like a wife might say to a husband after the husband risked his life, almost died saving her and their only son--that she could never imagine loving him less than wholesale and forever faithfully. It's not that she would no longer have any will in the matter . . . it's that said will would be freely but completely invested in one direction very faithfully and securely.
Certainly Holy Spirit has a hand in getting any believer to that point . . . The biggest part, I think.
Don't you think it shows great understanding as well as humility on Peter's part? He's come a long way at this point.
Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
You don't want anything to do with that guy