I have never seen that confirmed. Gasoline is a liquid solvent and NG is neither. I would want to see that in writing.
The yellow Teflon tape will seal gasoline. But tape is subject to installer error and if you get it over the edge of the threaded fitting strands of it can end up in your jets or oil system depending on where you are using it. Same with RTV, it can get everywhere in your engine when the excess gets squeezed out when assembling parts.
I like the old fashioned liquid Permatex too. It's strong enough that if you do get some excess in there it tends to stick and stay and not break off and circulate. That stuff has been around for 500 years and it's still better than most of the new sealants.