The fire part is a separate issue. There are other ways to desecrate the flag. I think you are missing the issue here.
I don’t think so. There are all kinds of things we don’t allow for good reason (Westboro freaks yelling on bullhorns at funerals, running around naked in public, for example). And I don’t give a darn how much nudists or feminazis scream that it is their “speech” to flash the world.