Andre, our silicon servo wire have a resistance time to kerosene of 20 minutes. After that, they start swelling up as you said. In practice they hold quite well in the plane as long as you wipe off an internal fuel leak. In any case that should always be done to avoid damaging internal components and risks of fire.
The PTFE cables are virtually un-sensitive to kerosene and quite flexible in 22 AWG, as well as much lighter than silicon HD cables. So, perfect choice for people looking for total resistance to kerosene. However they are twice the price of the silicon servo cables.