While I think that the PSK should be available in emergencies - that is the idea after all - I do think that any tool I am carrying should be useful and available whenever I need it. How you define emergency also comes into play here. Of course if I have three days of iodine tablets in my PSK and I use one of those days to continue my journey then my preparedness is reduced by that much but I wouldn't immediately interpret that as an unnacceptable risk that would force an abrupt halt to my adventure.

To be in the midst of an adventure and discover that my filter had broken or my regular supply of iodine tablets had been compromised or lost I would consider an emergency worthy of invading my PSK supplies. After having done so and thanking ETS for pointing out that my PSK should be with me and contain those supplies, I would then take stock of my situation and determine if I could continue safely or not.