Disabling the Airport in software (by turning the card off) probably won't prevent hardware problems. You would have to physically remove that airport card. The older iBook G4s have an Airport card just underneath the keyboard, and can be removed in less then 30 seconds. The last iBook G4 has an Airport card completely inside requiring major disassembly to get at, and more than 15 minutes to open up, then put the case back together for use, and only if you know what you are doing.
I would recommend removing the RAM memory card first, and see if that fixes the kernel panic. Access instructions to the memory slot is on a diagram printed underneath the keyboard. If the memory slot is already empty (very possible), then that's not going to help.
Quite often, kernel panics on an iBook may be caused by a failing hard drive - but - replacing the hard drive is a major task. There's 50 tiny screws to get at the hard drive (I've counted them a couple of times!), and the first time is really a "grand exploration"
Serendipity is a lucky guess !