Kay Steiger is perturbed by the idea that Ron Paul was using Guy Fawkes Day as a fundraising gimmick: "Ron Paul is associating himself with a historical figure who spearheaded a plot to blow up the houses of Parliament -- by very definition, a terrorist. True, England was persecuting Catholics and Fawkes role was to fight back against a religiously intolerant government, but he was still a terrorist by definition."
There's some interpretive ambiguity here, though, since the idea of Guy Fawkes Day isn't to celebrate Fawkes but rather to celebrate the foiling of the plot and I think it was traditionally observed by getting drunk and beating up Catholics. That, however, would also be a weird association for Paul to be courting.
On the other hand, V for Vendetta appropriates Fawkes as a kind of libertarian icon and it would make sense for Paul to appropriate that, so on that level it makes sense. Also: He managed to raise a lot of money, which was the point of the exercise, so it definitely makes sense on that level.