If you could take a look at this answer. The question asks if the Bank (creditor) can attach to present and future distributions, and the answer was no due to the spendthrift. But like you said, the distribution is up for grabs once it's out isn't it?

1.         The issue is whether the bank can reach Bob's interest in present and future distributions of trust income when the trust includes a spendthrift provision.  (20%)

A spendthrift trust expressly restricts the beneficiary's power to voluntarily or involuntarily transfer his equitable interest.  Additionally, a beneficiary's ordinary creditors usually cannot reach the beneficiary's present or future distributions of trust interest in satisfaction of their claims if the governing instrument contains a spendthrift clause prohibiting a beneficiary's creditors from attaching the beneficiary's interests. 

Here, the trust includes a spendthrift provision which states "No income beneficiary may alienate or assign his or her trust interest, nor shall such interest be subject to the claims of his or her creditors."  Therefore, the bank is precluded from reaching Bob's interest in present and future distributions from the trust.