Hello Mike,
The reason you should not open the Azodyl capsules is that they are "enteric coated". This means that the pill is intended to release its contents in the intestines where the medication is active.
The capsules are large and the difficulty of administering Azodyl to cats is a common problem. The manufacturer has said that the only way to guarantee the efficacy of Azodyl is oral administration; however, based on anecdotal evidence, they did mention that if the capsules are opened and placed on food they recommend giving a double dose. Therefore you CAN open the Azodyl capsules and place them on food, but just use a double dose.
You could also try following administration of a capsule orally with a delicious treat that your cat finds irresistible, such as a small piece of chicken. I have found that once a cat realizes that a reward is forthcoming, he/she may become more tolerant.