A better analogy would be that your son is relying on someone else to provide him with the thesaurus and that actually getting his hands on it is somewhat out of his control.

People need to stop mistaking milestones for promises. "Anticipating" and "Promising" are two different things. The company has always used the term "anticipate" to provide guidance on timelines. I've never read the word "promise" regarding any milestone.

I like the analogy of AMBS driving coast to coast and saying they anticipate arriving in 5 days. Along the way, they encounter more road construction than expected, a snowstorm, etc. Instead of arriving in 5 days, they arrive in 7 days. The most important part is that they still arrived safely, just a little later than anticipated (not promised).