One potentially bad argument for the need for infinite punishment comes from John F Walvoord, in Four Views on Hell. On page 27 he says "While on the one hand [God] bestows infinite grace on those who trust him, he must, on the other hand, inflict eternal punishment on those who spurn his grace."
Now it is possible that he means that without the grace offered, God has no choice but to inflict the punishment that has already accrued. I'm fine with that. But it is also possible that he means that the infinite punishment is punishment for spurning the grace itself. (The context does nothing to make it clear which he means.)
If it is the latter, that's horrible. Grace isn't exactly a free gift from God if the failure to accept it is punishable by hell, is it? In what moral system is it obligatory to accept grace?