The point is that they distributed AGPL licensed software which legally speaking puts them on very thin ice if they say "actually you're not allowed to modify that software we gave you and explicitly told you you could modify to do whatever you want."

This is a direct quote from the Affero GPL:

> When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work's users, your or third parties' legal rights to forbid circumvention of technological measures.

The thing Bambu is doing is very much against the spirit of the AGPL, which is the license they chose for the Bambu printer software. And the AGPL has such broadly written language it's hard to believe what they are doing complies with the letter.