I'm going to write a long, well-thought-out post on my opinion of this whole debate:
No eff that, malicious code = inexcusable. Full stop.
Seriously. My opinion on Gregtech or Tinker's Construct is completely irrelevant to the matter at hand, so I'm not even going to bother elaborating on it. The fact is, it is modder etiquette to never introduce code that will intentionally crash or stop a game from running. Full stop. There are no excuses for it. Debating on whether it is malicious or not, game-breaking, mod neutering, or taking the completely arrogant stance of "no one can tell me what to put in my mod, only I get to decide that" or who has the bigger e-peen is also completely pointless. That includes the platitudinous excuse of "there's a config for it" as well. This is pretty cut and dry - if you introduce code that intentionally makes the game halt, you lose. Full stop.
As an aside, if you do want something to chew on, most mods (not always the case, and with the growing popularity of FTB, even less so) are balanced against vanilla minecraft. That means that it is the assumption that any mod you use is balanced against vanilla recipes. If a mod changes vanilla recipes, then it is a total conversion mod and shouldn't ever be played with any other mod installed, because the balance will be off by nature. Put what happened into perspective given that is the case.