I'll recount an incident form 2006, so long ago that it probably is irrelevant to today's air travel security practices.
I took a Coleman Peak1 to New Zealand. Prior to departure, I left the fuel cap off and let it dry for days. Then I tested it by sticking a lit taper into the tank. Woosh, an instantaneous flame shot out of the tank, blowing out the taper. I let it sit another day and tried the same thing, and got the same result. After a couple days repeating the test, it finally had no more fumes and a lit taper stayed lit inside the tank. No more fumes. I packed the stove in my checked bag and used it while camping in New Zealand.
The return trip was a different story. First, I only had two days to let the tank dry. Second, the Kiwi TSA were more vigilant than their US counterparts. I was paged over the airport PA and taken to a behind-the scenes room by two uniformed officials. There, on a stainless steel table, sat my suitcase, beside a full size color reproduction of an image-scan of the suitcase. "Is this your suitcase?" Yes. Then one official pulled out a collapsable, telescoping, pocket pointer, ceremoniously extended the pointer, and tapped one end on a corner of the suitcase scan, "What's this?" Oh, that. It's my Coleman Peak 1. "Open the suitcase." I opened it and lifted the stove. "Don't touch it!" The other official prodded it with a small dowel, before gingerly lifting it out and putting it on the table, then telling me to open the fuel tank while they kind of stood back. Once opened, one official picked it up and smelled the tank opening. He got a good wiff of the fumes and shook his head. The Peak 1 stayed in New Zealand.
The scene at Wellington's airport reminded me of "Alice's Restaurant," officer Opie, and his 8x10 color glossy photos. I wasn't laughing at the time because I was scared of being in trouble and missing my plane. But, every time I think about it, I get a little chuckle.
The Kiwi officers did tell me that the way to defume stoves was to fill them with vegetable oil. I have no experience doing that and have no idea if or how it works.
If you've used outfitters at popular destinations, perhaps you've been offered partially filled fuel bottles. The standard practice for taking stoves on airplanes is to use a stove with a separate fuel bottle. Travelers purchase the gas bottles at the destination end of their flights. When their river trip ends and air travel is imminent, they leave the partially used bottles with the outfitter. So, many outfitters have a supply of partially filled bottles they are happy to get rid of.