Lighters are not forbidden. I was told to toss out all but one when coming back into the U.S. from Canada, once, but that's about as far as it's ever gone. I travel a fair amount and almost always with one or more lighters.
Having said that, these rules are usually not strictly enforced.
One lighter on a person means a problem will be relatively small and quickly noticed.
https://www.faa.gov/about/office_org/headquarters_offices/as...