How would you deal with this situation? DMs unite.

[Vagnarok]

I think this part needs to be left out though. Using the PC's class as a justification for behavior just smacks of bad character writing.

I'll agree with you 50%. IMO all classes tend to draw people of certain personality types. Considering that PCs are already rare in the game world, PCs that go against class-personality stereotypes should be rarer still. Paladins acting lawful and Rangers liking nature fits this argument quite well I think.