Jogro the resin DO NOT need sub freezing temperature to fall, they have been designed by mother nature to fall by themselves at maturity or at the touch of an insect.
"An abscission zone develops at the base of the head where the stipe cells attach to the disc cells resulting in abscission of glands upon attaining maturity"
THC (TETRAHYDROCANNABINOL) ACCUMULATION IN GLANDS OF CANNABIS (CANNABACEAE)
Paul G. Mahlberg and Eun Soo Kim, Department of Biology, Indiana University, Bloomington, IN USA; and Department of Biology, Konkuk University, Seoul, Korea
"The "problem" is that with dry ice the leaf material quickly freezes and starts to pulverize into dust" you nailed it here Jogro and it happens very fast
It does not happen with water and does not when you dry sieve either.