Once you're done amusing yourself on this lovely Friday afternoon, give Christopher Tollefsen's interesting argument against Terry Jones' (the infamous Koran burning pastor) a read.
Tollefson's basic point is that Jones is morally culpable for being lethally reckless, on grounds that he foresaw potentially deadly side-effects to his action and yet proceeded anyways:
Such side effects were foreseeable and extremely grave, yet Jones did not reck them; his actions were reckless, and lethally so. And in consequence, while he did not cause the deaths of those innocents, and while his own culpability does not mitigate the responsibility of those who did cause those deaths, he bears a not insignificant moral responsibility for those deaths.
Senator Graham is, I believe, absolutely right to wish that there were some way for Jones to be held accountable. There appears not to be, legally, however, and perhaps this is for the best: upholding and applying a law that forbade the burning of holy books might be overly intrusive, and might be in tension with constitutionally protected rights. But Jones should not be allowed to hide behind his right to free speech to shield him from moral blame, nor should he be allowed to hide behind the only apparent gap in gravity between what he did, and what was done by the rioters. Willingly to accept the risk of such great damage to innocent human life for such a meaningless bit of self-expression is a morally grave wrong, even if it is not the wrong of intentionally killing the innocent.
What I like about Tollefsen's case is his narrowing of the forseen side-effects that we are, or are not, morally accountable for. There's a subtle argument going on here about the "doctrine of double effect" and when and where it applies. Tollefsen's suggestion is that we're culpable for unintended negative side-effects when our intended actions are either morally wrong or not-obligated at all.
The only way through, I think, is to suggest that Jones might have forseen potential attacks on himself or even on his church, but not on totally unrelated parties. There may be, for instance, a sort of "moral proximity" case that might suggest that the spheres in which the side-effects occurred are so far removed from the action itself and there are so many layers between his action and theirs, that he can't be held accountable for them.
However, whether that rejoinder is plausible is very much an open question.