I have a major problem with this. Because it wouldn't stop with Phoebe. It would just escalate whether she escaped or got burned to death. That is the nature of witch hunts. Humans are not particularly bright creatures en masse to begin with; add fear and panic into the mix with some self-righteous asshole stirring up shit, and you have a recipe for continuation of idiocy. So pardon me, makers of Charmed, but that episode just doesn't make sense.
Now if they'd said that the point of coming to this point in the future was to have the value of forehindsight (hindsight before the fact), and thus prevent the whole thing from happening in the first place, then I could buy it. But no, they give some BS about "it must stop with Phoebe." As though a witch hunt would just go away with one televised execution. Sheesh!