Drawing different sources of information together into a single understanding is quite literally the definition of "synthesis" in this context. If that process is what you're referring to as "re-sequencing content", then it does fit the definition of "synthesis" in this discussion.
If you're using the phrase "re-sequencing content" as a way of indirectly suggesting that LLMs aren't relating together multiple sources of information and combining them into a single expression, then that itself is the point of contention that we are arguing about.
Perhaps you're trying to apply a philosophical concept of synthesis, e.g. that of Fichte or Hegel, but that definition applies to a specific type of philosophical analysis, and isn't quite the concept we're using in this discussion.