Not sure what you are up to or the reason you're doing what you're doing, but as Rick says, it won't hurt the seed, imbibed or not, to freeze in your starter medium as long as it's not ridiculous. In fact, rechilling and/or refreezing a stubborn hard to germinate seed lot for an additional 3 to 4 weeks is an old timers trick to really get things poppin'. To understand why imbibed seed will not or won't sprout is most likely because the soil media is/was too warm for this particular seed. Therefore, after rechilling, try germinating at a lower than the usual 65-70'F. Try 50-60'F. It works.
