I have not had any issues with them. I just use the freezer and keep the seeds in there for a few days then put them in a glass jar. Now I only have the one seed mix and Pip's millet and the millet went through the freezer too and into a plastic sterilite container. I also put my pellets through a freeze cycle and into a jar too but I doubt they would have an issue anyway.
I guess you might be able to vacuum seal the seeds and suffocate them as they hatch but so far I have not had any issues with the freezing method but like I said I only have the one jar of seed mix. I dont give Pip very many seeds so even a pound lasts him over a year. I will have to get new seeds for freshness before he ever runs out but at least the outside birds will get a treat.
If you get some moths that get outside into your house they make a moth trap. I have never used them but supposedly they attract and kill the males so they can not reproduce and die off over time.