I guess I disagree with Rothbard. It doesn't make sense to me for someone to be liable for something he didn't personally do unless this state of affairs is changed through contracts. Why should one certain type of contract have the implicit meaning that one side of the contract takes some liability from the other side?
You can disagree with Rothbard or existing laws as much as you like, but the real world exists and you're bound by its laws. Even if mere "shareholders" in your Franken-company had no liability for the entity's actions (and if they voted in favour of the company pursuing illegal activity they would likely lose any protection from liability), office-holders have specific and well-defined liability in respect of the organisations in which they accept those roles, as do people who participate in management activity whether or not they are formally designated as office-holders.
You obviously realise all this because you didn't want your name legally connected with a "legitimate" GLBSE. You were mistaken, however, in assuming that just because GLBSE is a "pretend" company, it's partners don't have any personal liability for its actions. This is a mistake I've seen many times in the Bitcoin community. Instead of getting proper legal advice
before launching Bitcoin enterprises, people just go ahead and operate them according to how they
wished the law to be.
Whether or not you think you
should be responsible for the actions of GLBSE in no way changes of whether you're actually responsible for them at law. You don't get to cry "that's not fair" just because you exposed yourself to that liability either willingly or out of ignorance. "But why" is what little children ask when they don't like an answer. "How am I going to deal with this" is the adult question you should be trying to answer.
"The company" is a myth. No company exists. At best, you have a generic partnership and that means that the partners are personally jointly and severally liable for the actions of the company. "Jointly and severally" means that every single one of you can be held 100% liable - your liability isn't even limited to the percentage of your ownership interest. Even if you'd had a limited partnership, the limited partners (whose role is effectively that of shareholders) would only be protected from liability if they confined themselves to specific "safe harbour" activities in respect of the partnership.