Those two statements (Intel won't take backorders on MAX10, Intel will support MAX10 until 2032) are not inconsistent.
You must understand that Intel is producing FPGA parts as fast as its fab allows.
But they are all being bought up by large customers who have prenegotiated purchase contracts for confirmed delivery.
There are no parts left that Intel is producing that can go to distributors for general distribution.
This is not just an Intel/Altera problem, it is affecting all semiconductors.
Heck even the car makers had to cut production because they could not get devices that they needed to produce car electronics.
So Intel is not going to accept backorders on parts that they know they can't produce for a year or more.